I wouldn't criticize someone's clothing to their face... but I might talk about it to other people (whom they didn't associate with and whom I trusted) after the fact just to vent. I mainly dislike people walking around with their pants down around their knees, with boxers showing. It's really annoying, and they have to use one hand to hold them up. It's so ridiculous.
Also, one person I knew wore these really ugly pink shoes with holes in them (I think they were called Crocs), and yellow eyeshadow. I kept wondering if I it was a bad idea for me to be seen talking to someone dressed that way, and then chastising myself for being selfish, judgmental, and shallow.