I just have to say, after reading this, I feel like a terrible writer. I know I have done/do many things people don't like. I mean, I know I can't please everyone but I think I get why I struggle to get readers.
Anyway, What turns me off of a comic?
Honestly, I would say art does turn me off a comic, but not if the story is great. I'll give any comic a good read to see if the story is there. But if the story can't "pull up" the art, I'm out. (Example of great stories with meh art: Barry Ween or XKCD) Also, yes, I know that this is totally subjective.
I'm also not a fan of the vertical scrolling page thing that's so popular now. I think it's hurt pacing and storytelling. I'm not saying it's garbage and should go away. I read plenty of comics in this format. But too often I find when a moment should be building action or moving quickly, long gaps slow the pace. People seem to have forgotten that negative and white space have an important role in how you read a comic.
That's it for me. This post has really given me a lot to consider about my own writing ... so much room for improvement ...