I don't like predominately white costumes; I just find them dull. Yellow rarely works for me, either, especially that one Sasha wore for her SP last year that could have been picked up by satellite. However -- I did like Barbara Fusar-Poli's gown from their 00-01 OD, and Susanna Poykio I recall wore something at least moderately yellow at some point that I thought was quite nice. Gold and silver lames have also gotta go. And HOT PINK. Or pink period, actually, for the most part, tho I will allow that that could be a Guy Thing.....
Other than that, it's rarely the COLORS of the costumes that get to me as much as the anywhere from 10 to 100 pounds of spangles, beads, toys, tokens, coins, feathers, Christmas ribbon (see Maniachenko, Galina, long program, last season, I think,

), rope, stuffed animals, car parts, food processor attachments, etc, that might be hanging OFF the costume. Way too much to look at. And the Blanket On A Clothesline During A Hurricane thing has gotta stop in Dance as well. I think part of it is deliberate because maybe some couples figure sloppy footwork won't be noticed as much if the judge's eye is distracted by a mile of fabric flapping along in the breeze behind them.
For the most part, tho, you can't go wrong with either black or blue; I can't think of anyone who doesn't look good in these colors. Just as long as they're not put with another color that's hideous.