Can anyone tell me why some photographers have yellow or blue scotch tape on their cameras near the flash?

Haven't seen that before. Is it a pop-up or a hot-shoe flash? I'm guessing it's a hot-shoe flash. Tape might be used to attach a bounce card or a color gel filter. Doesn't seem like a good idea though, as the flash does get hot, and the sticky part of the tape might stay on the flash.