I have read the whole thread, and I'm a bit shocked that some think that to refer to somebodies skin colour is racist when that are the only person with that skin colour around. I have been in lots of situations where I have been the only white and have been referred to as such, in friendly/unfriendly/indifferent ways depending on the context. I have been annoyed when people have sucked teeth at me, that I shouldn't be there (night club, only white person) but I didn't mind being stared at, because I did stand out.
Anyway, I have always thought in a situation like the op describes avoiding using the term 'black' is more racist because there's nothing wrong with being black so why wouldn't you use it. A friend who used to work at SS told me that she wasn't allowed to say 'black coffee' or 'black board' because it was offensive, this was years ago though, I can't imagine they still do that, I thought this was ridiculous, and besides she said they replaced the black boards with white boards.
I now live in Devon, so very white English around here, which may colour my view but I'm really trying to see your point Amber I will re-read and think but to be honest I don't think I would want to stop describing the only black person in the street as black to somebody who didn't know him because it's just easy. Maybe that's very lazy of me, maybe it's even racist of me?
I do think however good our intentions we can all be racist in ways we don't realise (including you Amber) I don't think the OP was though... will think some more.