A few times, I've been keenly aware of the insider "buddy-buddy" thing that some guys give me in retail and service situations. These men are not quite like that with the women. I don't know if you would call that sexism.
A few times, I've been in similar spaces and have been noticed by a male clerk or sales representative who basically ignored a woman and targeted me. I always wonder if she has been there awhile browsing; I figure maybe someone has already asked her if she needs any help, but I wasn't there to see it. I feel very awkward when this happens.
A few times, women have been irritated or exasperated by something I've said or asked. I didn't perceive my statements and questions as particularly egregious or stupid, but they came from a clearly male perspective, so the women reacted in a particular way. I kind of felt like I was on the receiving end this time--of anti-male sexism.
A fellow in my men's group has trust issues with women, and he once said that he felt that women were manipulative and sneaky. Well, I can see that. In a sexist society, girls tend to adopt certain strategies, like indirect aggression, to compensate for their lack of overt power. So they do all of this clique stuff, talk about other people behind their backs, spread rumors, stuff like that. This is how they compensate. I don't particularly like that kind of behavior; I prefer the direct approach.
Indirect aggression has been well documented in women and girls, so I don't think a guy is sexist if he merely points out that a lot of women behave that way.
I have my own issues with women, but it bugs me when guys say truly unfounded things about them.