I think wearing a lot of really obvious makeup and having an overly fussy hairstyle is a big giveaway. Guys would probably also think a girl was high-maintenance if she was consistently over-dressed for things, like wearing a dress when other people are wearing jeans or something like that.
Some girls just ooze "fragile, too picky, complaining and judgemental" . those are the ones I avoid and consider high-maintenance. If they are followers of trendy stuff and overdo there looks, it gives the impression that blending in and following the crowd means everything. They are the ones too good for the universe and picking guys that look good and will follow orders. Bleh.
Owning a massive amount of designer clothes that varies from day to day; wearing real jewelry, not the fake stuff; obviously spending a lot of time fixing their hair and face; and topped off with an attitude. Definately high maintenance.