I have a black r34, don't expect it to look clean for more than a day or two. I give mine a good wash on weekends (takes 2-3 hours) and depending if i have to go out and the amount of bird crap on it I'll give it a quick wash in the middle of the week. (40 mins)
Maybe it's just where I live but dust/pollen just covers it over night.
Here in WA a major problem is our heavy water, you get spot marks no matter what. (I want to hurt the person who designed the sideviews that just drip for hours)
Stone chips show up really bad, I have like 3 of them on my bonnet they make me
Sometimes I think I should have held out for a bayside blue one but then you'll walk up to it sometimes and just think "omfg thats sexy" and it makes it worth it.
Only midnight purple looks better than after it has just been waxed/polished IMHO
Depending on the car I think I'd get another black one.