Welcome to Orchid Board
It does look like some of the roots are rotten, but others look good. The colour of the roots does not matter too much, if they are firm, if they are hollow or mushy that's when you have a problem. Some of those look as though they should be firm from the picture.
I agree with Bud's advise, but I would be slightly more worried about the dark spot, however his advise on what to do if it spreads sounds good to me as well, and if it doesn't spread then I wouldn't worry.
Good luck!