I think I would find it from strange to rude if someone came up to me and started criticizing my outfit without me asking them to. I could be thankful though, if it's constructive criticism, though maybe not at that moment . Then whether I would find it offensive or not depends obviously on how it's worded. If someone came up to me and told me I looked like a two cent hooker (like someone commenting on some poor girl's outfit wrote in this forum) then I mean, how could I not? And I also hate patronizing comments, so those could also offend. But I usually stick to my grandma's advice, if you don't have anything nice to say, then why say it all?