The way that IPL and laser work is that they heat up dark hair more than the skin around it because dark pigments heat up more, which then torches the hair. In the case of laser, this actually includes permanent destruction of the hair follicle if done right, in IPL it usually doesn't because the impulse doesn't travel as deeply underneath the skin. As you can see, the core part of the concept is a contrast in coloration between the hair and the skin. This is why these treatments do not work on platinum blonde or grey hair, and why they are extremely difficult on red hair. This is also why they can cause bleaching on dark skin. That isn't something that usually happens when you're a cracker, and i know a Mexican girl with light olive skin who gets laser without problems, but my laser technician still used to cover up my birthmarks with a kind of light pencil when i got laser hair removal.