@vothnthorvaldson I replied to some of your questions but ofc reading it is optional and you don't owe me a reply.
Personally I don't think most people who give unsolicited critique have bad intentions, I think they probably just want to help. It's not about the intent but about the effect though. You don't know what headspace the person you're critiquing is in and what effect receiving your critique at the moment where they receive it will have. That can easily be prevented by asking if they want feedback, because then you'll know and they will have the opportunity to mentally prepare to take in criticism and learn from it.
I do think there are bad faith critiques out there, there are people giving intimidatingly detailed, complex and overwhelming critiques with detailed advice meant for advanced artists to beginners. That combined with using terminology like it's part of your everyday vocabulary, name dropping of certain experts like you've studied them all, and just a certain manner of speaking (or writing) just comes across as "I am an expert so let me give you some advice but mostly look how knowledgeable I am I am so smart and such an expert." Usually it's more information than a beginner can process so while the critic could just not know better I get the impression that this does also give them an ego boost and they like to show off at least subconsciously. Nothing wrong with that, except when it's at the expense of another artist who might be flooded with things they must improve and things wrong with their art that take years to learn.
As for the public vs private thing, personally I prefer public feedback. Receiving an unsolicited DM (if the person asks first and says they just prefer DMs) it's no problem) with feedback will, first and foremost, make me wonder why it's private instead of public. I can think of three possibilities: 1) It's inappropriate in some way, it crosses certain boundaries and that would make me uncomfortable 2) (which is more likely) it contains so much criticism that the critic feels bad about posting it publicly because they don't want to humiliate me. Aka my art is so bad it can't even be critiqued publicly. That would make me anxious and feel pretty bad about my art. 3) The critic might just be a little too anxious or self conscious about posting publicly. No big deal. But there's always the possibility of number 2 being the case, so I would be a little anxious initially. Doesn't have to be a big deal but it can be prevented by, again, asking first.
Another reason why I prefer public feedback is that it can be pretty biased and bad advice even if the critic means well. I've seen this happen twice, one time it happened to me when I was an insecure impressionable teenager, and I also saw it happen to a young writer. Here's the thing. When I was younger, I'd be intimidated by every self proclaimed expert who was older than me. I'd take everything they said at face value because they were older and more experienced, they knew better, right, and I didn't wanna be a little bitch. I was also unable to distinguish between honest but polite constructive criticism and destructive criticism. One time an artist told me that my pencil portraits aren't real art because they're copied from photos, that there is no creative process in them and being able to create them is a basic skill and nothing special. Then they told me what I should actually do to be a real artist, which I just couldn't do at that age. I didn't have the means. I was young and impressionable, and I probably would have believed that my drawings are worth nothing if that had been the only feedback I'd received. Luckily there were other artists who opposed this person, and so it became very clear that their opinion was just that - an opinion, and not one many people shared.
Then there was a guy on a German writing forum who was convinced that German novels should always take place in the German speaking world and nothing else will sell (which is just not true), and told a teenage author to change their story's setting (their first story at that) because otherwise they'll never be able to publish. This writer didn't know much about writing or publishing so without other people chiming in there's a possibility that they could have believed him. I don't know that for sure but I know I would have at that age and I know other people who said they would have believed it.
Those aren't the only two instances of biased feedback and advice I've received or witnessed, it happens a lot and I'm sure I have given biased feedback. It's always a little biased, especially when it's unsolicited and the person being criticised never said what they were going for, and you simply can't know how someone else will take the feedback. Even if you would be level-headed about it and able to spot biases, that doesn't mean everyone is, especially when it comes to younger artists with less experience. It's important to keep in mind that there's always the possibility of someone just taking in everything you said without questioning it and it actually being bad advice for this person in particular. So yeah, I think public feedback is a good way of preventing that because you get more than one opinion, and if someone's feedback is unusually biased, other people can respond to it and point that out. The critique can be critiqued as well.
@indagold I hope it's okay if I respond to you (if not I'm sorry and feel free to ignore it, you don't owe me a reply) but you seem very frustrated and I don't really see the connection between you wanting critique and people not liking unsolicited critique. Why do you think you wouldn't have improved as much if you'd asked for critique? Shouldn't the opposite be the case because then you'd receive more critique to learn from?
This is about unsolicited critique only because that can be directed at someone who doesn't want it and/or can't currently process it, and there are many reasons why someone might not want criticism (usually temporarily) that has nothing to do with just not wanting to acknowledge that their work isn't perfect. I think most people are aware of that tbh.
If you want criticism, it's easy to ask for it and say that you don't care much for praise. You can also add that any criticism, anything that stands out to people, is welcome. If people then still give you just praise, that's a dick move, just like unsolicited criticism. Not every positive message has a positive effect, especially when the person receiving it specifically said they don't want it (I've been on the receiving end of positive messages that did more harm than good that I specifically said I don't want) so yeah, I get why that would be frustrating. It's someone else imposing their opinion on what your mental state should be on you and even if they mean well, they fail to acknowledge your individual experience and needs in that regard and that you are not the same as them. So yeah, if you ask for criticism and all you get is compliments I get why that would be frustrating.
But your experience isn't the only experience either. Just because you can't think of any other reasons why someone might not want critique or those reasons don't apply to you that doesn't mean everyone else is or should be or think like you. Just because you're grateful for critique that doesn't mean everyone should be. Just like other people shouldn't generalise and make assumptions about what you really want or should feel like you also shouldn't do that to other people.
Also, "people want you to improve" doesn't really matter unless those people are paying you. What matters is if the artist wants to improve. Not everyone's goal is to improve. That's okay.
By the way, reviews are meant for potential consumers, not the creator. If you review a book, it's not primarily feedback for the author and it's usually not directed at the author but at potential future readers. Usually it's posted on websites for readers, not writers (though some writers will obviously be on those sites and look at their own reviews as well). The author can read it, learn from it or ignore it completely. Unlike a comment on social media or a DM, they have to seek it out to read it, so it's entirely their own personal choice. That's why there's a difference between critical reviews of media you pay for and unsolicited criticism on someone's art or fanfic that they post for free, that's meant for the creator. A critical review of Gabbie Hannah's poetry book is not the same as posting a lengthy critical comment on some online writer's free to read poetry, especially when you know nothing about that writer. For all you know they could be a 14-year-old kid completely uninterested in becoming a professional writer who's just using poetry to cope with their abusive home life. You don't know so it's best not to make assumptions.
Again, this entire thread is just about unsolicited critique and online etiquette when it comes to feedback. All of this "should I say something or not" and careful praise can by bypassed by communicating what you want to hear. "I know my art isn't perfect but I currently can't process a lot of feedback so please don't leave me lengthy critiques, it would be a waste of your time and overwhelming to me" or "I know my art isn't just atrocious but I'm only interested in what I can improve so please don't go out of your way to compliment me, it would be a waste of your time and frustrating to me", or anything in between. There's another conversation to be had about toxic positivity and people imposing their positivity on others, which I don't think is okay either, so you touch on an important point there, that just hasn't been addressed in this thread yet.