Yep, sure are. They're all over the place. Just look through the comments in pony videos on Youtube. You're sure to find a few bashers there.
As to why they do what they do? They have their own reasons. Some of them are probably going through some 'stuff' and feel the need to lash out. Other people might do it to make themselves feel better about themselves, actually that'd be about 80% of them. Ya know, approximately. xP