Why do people look at me like this?

Ok I wear alot of abercrombie and hollister and american eagle clothes. SO does my bf and somtimes when we go to malls some people who to me look a little trashier look at me like ewww. But i am a size 4 in jeans and medium in tops. But i look good not fat but not super skinny. But i just honestly do not get it. Can someone give me a hint or maybe just y they do this?