it could be because they have mites... snakes will soak themselves in an attempt to drown the little bastards mites can be very serious if you let them go on for to long you should check your snakes over very closely and possibly ask a herp vet
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1.1 rosy boas
1.1 suri red tails
1.1 gopher snakes
1.0 iguana
1.o cali king snake