I think this is why a lot of people see them as spam..! Because the threads have become drop and go instead of people hanging around to chat and ask questions about each other's content. In and of itself it's not necessarily spam, but it can definitely feel like it when you see it over and over!
Engaging with others is always a lot better than spamming a link I think. I really like mutuals because it creates a better dynamic for engaging vs. following a bunch of people I don't feel a connection with. I've made so many friends in the comic community this way, and found a lot of great comics I'd never have looked at otherwise just because they wouldn't have appealed to me on a description only basis. I highly encourage others to engage vs. just posting a link and running as well since it's through engagement that connections and friendships are made 
As the creator of the greatest sub thread in all of history (including but not limited to all the multiverses)...
I feel I should note that it's also a question of most of us not being really great at pitching ourselves/our projects. We just post a link in these threads then silently slink away.
Where's the showmanship?! The Razzle Dazzle!?!
Maybe we should burn the approach down and rebuild it from the ground up!
I've seen a couple attempts where you have to give feedback/sub back, but not very much. I'd LOVE to see threads where it's in the rules that you should interact/reply to at least one person and start a conversation. Maybe you find a new comic/novel you like, maybe you make a new friend, maybe both!
Spamming isn't really worth it imo. It's awesome to share your link in a thread that calls for it from time to time, but I don't think you can gain much from mindlessly spamming it everywhere. I think posting meaningful things and holding interesting conversations with other members is much more effective in my experience.
Mmm yeah, I feel like people more likely to checkout longer promotions with their artwork and info on their comic. gotta stick out from the links. Is why I started leaving an animated picture from my comic when I'm on these promotion threads.
I've found the most effective way is to never share your comic in multiple "share your comic!" "comics under x subs!" threads all at the same time. You need to spread it out, because different people are on the forum at different times or on different days, and spamming comes across desperate and pathetic, like you're unable to get readers, which will make people perceive your comic as "low demand" or "less good".
Prioritise threads where you post sample pages. I pretty much never miss the "post your latest page [month]" threads; those threads are some of the most useful; a page is worth so much more than a description (I also frequently have found new comics to read on those threads). Threads where you post things like work in progress to finished pages or pick out the funniest or coolest page or funny panels are also great. They're more effort, but that's the point. Minimal effort copy-paste spam posting the link and a blurb in a bunch of threads all at once, then being completely silent the rest of the time and posting in no other threads is highly ineffective, especially because most people on "share your work" threads are only there to promote themselves.
I don't spam at all. In fact, I barely advertise or promote my comics after the first few times I've been on this forum.
Whenever, I post in a thread like this or this, I always tell users to refer to my profile instead.
That way, I can stay humble and continue what I want to do without gaining much subscribers.
And yeah... quote...
Wow, as i'm for another time-zone i didn't see this coming xD (it took a while to read all of your resposnes^^')
As she said:
@WolfUnderTheMoon89
This was an enlightning thread, thank you all for that!
I'm glad then that I was pointing to the right direction 
Thanks you all!
)
And it's especially good,
when author becomes reader and reader becomes author,
the joy and wonder becomes double,
and they find new details, without trouble.
No, it's not worth it (at least to me). When you could spend that same time actually interacting with the community. I see no reason to post a link to my comic every single chance I get, every single day, when I could just as easily get to know other creators here with legitimate conversations and build myself up that way. Not to mention, you're making friends that could really help you out. Even teach you.
Now, I do see a difference between an active user who just happens to also be sharing links should the opportunity arises, and a user who spams and only uses the forums to post link after link. This is a forum full of creative minds, after all. Not a bulletin board.
If i had to be him, i would do like this xD3.
But i'm actually a little trolly with this things xD
OMG you got me good right there @neardrive