Taking Stock of the Stock Art

I've been trawling through stock art sites in hopes of finding something suitable for the ebook release of Aristoi, and I'm finding that there are certain images that appear over and over again.Bald heads, for one.  If there's a person without a helmet or something covering his or her hair, ten to one that person's bald.I don't think this is because science fiction artists have a strange fetish for bald heads.  I think it's because hair is difficult to paint using Photoshop or other...