just answering about Kelis's hair..it's possibly a lace front wig. Most celebs wear weaves, including white celebs (not a full head maybe a track or two for thickness) and the whole reason for it is so the cameras can pick up on their hair better. You don't wanna have see through areas in your hair while you're on TRL lol. And if it is her real hair, they usually photoshop the hair too if it's not full enough, or if there's some curls that aren't laying just right.