I use 4" PVC couplers to hold the disposable cups...this way the snakes don't knock them over they just slide them around. When it is time to change their water just pop in a new cup...no mess no fuss.

The cost of the cups new is only about 5 cents in bulk which is cheaper than the soap and time combined to clean them (and there is no risk of soap or bleach not being rinsed away well enough and the snake ingesting it).

I recycle the used ones as well.