i think it depends on the guy AND the girl. if the girl can pull it off and is confident wearing it (and it's well-applied), then chances are other people will think it looks good. at the same time, some guys just don't like color, especially bright color.
most guys like what people call the "natural" look, even though that doesn't necessarily mean the makeup isn't heavy. this basically means foundation/concealer to cover any imperfections, neutral brown eyeshadow, black mascara, maybe some peach blush, and a "your lips but better"-colored lipgloss that adds a little shine but doesn't look over-the-top glossy. chances are, as long as the face makeup looks good (meaning, not cakey and matches your skin), a guy - or anyone, for that matter - isn't going to say you're wearing too much makeup or that it's thick, even though it very well could be. the "not hiding behind a mask" is a cheap excuse, because if your skin looks flawless, i doubt anyone's going to be complaining. ;]
most of the guys i know say they like my colorful eyeshadow, but there are a couple who are just like "...why do you do that?" i always just say because it's fun and i like it. :] like painting on your eyes, haha. plus, i'm the one who has to deal with it on my face!
