I changed the original thread title to avoid the chance of a beginner snake-keeper just skimming the first post or two and believing that cooking spray was an affective mite treatment.

To answer the original question OF the thread title...

P-A-M works because it kills mites in ALL stages of life, including eggs. Most pet-store remedies will kill the ones you can see on the snake, but won't touch the eggs that have been laid and are too teeeeny to even know they're there. A few days or weeks after treatment, you have a whole new crop of mites to deal with again. P-A-M frequently only requires a single treatment (except in extreme cases) so long as it is used correctly.