Sometimes I get a strong sense of someone's type by the avatar they've chosen.
I enjoy looking at beautiful things so I enjoy the pretty avatars the most.
I enjoy the funny ones, like edcoaching's approximist/perfectionist avatar.
I don't care for the ones with blood or violent aggression, etc.
I just use my Firefox Adblock Image feature to block them because they're distracting and can give me bad feelings.
I have not noticed anyone treating me differently, but I believe I've only had two avatars and they've both been of waterfalls.
I choose waterfalls because they are one of the most beautiful things on this earth that I enjoy.
I don't believe someone's avatar has much influence on how I respond to them in a post, though I would assume it must to at least a small degree, since I am not a robot, and as I said, I am very visual.