Maybe I've been super-lucky, because I haven't had that many negative reactions.
My family is very supportive, and most people I show the comic to are really impressed - mostly because most of them have no idea how to draw, and are deeply impressed by anyone who can. I went to school for Comics and Visual Storytelling, and met a bunch of fellow comic artists through that, which is nice too!
There are some people who just shrug, but then there are some people who just don't enjoy comics in general, so whatever.
My one and only genuinely negative experience was the one I refer to as Sword-Guy. He came up to my table at a con last year, picked up the preview booklet for Grassblades, and without even reading the actual contents, launched into a long tirade about how lazy and terrible I was for not drawing 100% accurate swords in my comic, and gosh he was so sick of people not doing research properly and why did people draw Japanese swords so much didn't they know that European medieval swords were inherently better because medieval Europeans were just smarter and better people than the medieval Japanese and blah blah blah blah.
I just stood kind of speechless at my side of the table, because I had the worst cold and my nose was dripping and I was running a fever and I wasn't entirely sure I wasn't just hallucinating this idiot. He went on for FORTY MINUTES, then dropped the comic and went away, only to come back TWO MORE TIMES - the first time to reiterate his "critique" of my comic, and the third time to, uh, argue about philosophy and René Descartes? I'll be honest, I'm not 100% sure that last one happened, because it felt unreal. Happily, my tabling-neighbours were really sweet and gave me candy and a pep-talk after he'd gone.
I asked around afterwards, and it turns out Sword-Guy does this every year at this con, to anyone making comics with swords in them - and that he's apparently somewhere on the Aspberger's spectrum.
... This year, I'm going to be wearing a badge that says "Don't ask me about swords". =.=