Ya you shouldn't clean the cage after spraying it. it will continue to work in the cage on the mite eggs. Let it dry though before introducing the animal really important!!!The hardest part of getting rid of mites is breaking the life cycle of the mites/killing the eggs which is my understanding PAM dose well. PAM used incorrectly can do neurological damage like seven dust or any other pesticides.
It is my understanding PAM should NOT be sprayed on the animal that soaking the animal with a dash of dish soap added to the water should be sufficient to drown the mites on the snake. I have not used it myself but from what I have read and talked to people about it that is how they do it. hope that helped
Chuck