Say what? Non-matching panties and bras!? At first sight of such an abomination, I would have to show her the door!
Just kidding. I don't care. Most of the time they aren't visible, and the only time they are is when... you know, they are about to come off. Good luck finding a guy who is that shallow and materialistic, I'm sure they exist under a rock somewhere.
It's generally not high on the list of concerns for a guy at that point in time. To us, it's like wrapping paper on a Christmas present; yes, we like the wrapping but we're more interested in playing with what's underneath. Of course, a sexy matched set will make us stop and think "holy s**t, that's hot", just before ripping it off with our teeth! :)
However, how it feels to you is even more important than how it looks to us. I dated one girl who felt a lot sexier wearing matching bra/panties, and the difference was *definitely* noticed in the bedroom. A girl's interest and enthusiasm during sex can overcome pretty much anything that could otherwise possibly kill the mood (non-sexy clothes, telephone interruptions, police shining spotlight on us and telling us to stop doing it in the park...um, was that out loud?). So if you feel sexier for wearing a matched set, go ahead and do it.
its OK not to have matching bra and panties. I been with girls that have not had matching bra and panties and its been OK with me. But I been with girls who had matching bra and panties and it makes them look more attractive because they actually care about little things like that. To me, a girl that does not match her bra and panties, let alone colors that do not match, shows me that they either don't have any matching at all, or don't care. So yes, it is attractive, personally I like it. But in reality, I don't care...your money, your choice.