It's subjective.
Personally, it depends on her figure ... And if you're talking body paint, latex, or clothing (and then, what clothing).
Is black a sexy color on a girl?
I don't think any colour is attributed to 'sexy' .. There is a huge difference in how 'sexy' a lady looks in a pair of oversized black sweat pants and sweatshirt in comparision to a tight black dinner dress. The colour is what not makes it 'sexy' ... the style and the fit would more than the colour.
A sexy person knows no color.
