I don't all out drop comics often, but I think if the comic I'm following just suddenly...completely jumped the shark on the story. Like, not fun little filler stuff (I get people need to go on hiatus), but if...I start out reading a sci-fi story, and it suddenly becomes a rom-com with little to no sci-fi elements. That's a bad example, but it's kinda the extreme change in story I'm trying to say would maybe, possibly put me off XD
(Like I ENJOY Rom-coms sometimes, but if that's not what I signed up for.)
Or if the series just completely stops and only becomes side art for seeeeeeveral posts of just concept art. Again, not a hiatus thing, just the author lost interest, but seems to not ever plan to continue the story. I dunno, it's hard to judge when that happens, so I rarely unsub in case I'm surprised and the person comes back.
Or if the story does something completely off-putting with no reason or seemingly no connection to why it happens. But even then, that's a stretch. The main character does something completely out of character and horrible, and there's no plan to explain why? I mean, it take a lot to make me unsub...and even then I'd probably try to wait it out to see if there's going to be a reason before I get ticked and unsub.
ahem I will unsub if I somehow manage to notice the author is actively an *sshole. I usually don't dig into what people are saying outside of a comic, but if I happen to know they are jerks, that will turn me off from wanting to support a comic. But again, I don't...really look much into writer's lives because I'm too busy minding my own life XD I haven't got time to keep tabs on other people. But if it's glaring and I happen to find out, I tend have trouble justifying why I'm supporting that person
This has not happened yet. But it's on the table for unsubbing (like if the person committed a horrendous crime, and I somehow find out, I'd drop it like a hot potato).
Those are probably the only reasons. I'm pretty mellow, and I know a lot people here are like me: independent artists/writers, and still learning, so I tend to give a lot of leeway, even if they've been at it for 10+