funny question here..

hey i got a corn snake in December and everything is working out perfectly. she eats fine and sheds in 1 piece. im pretty sure that corns instinctively feel the need to defecate when put in water so would it be bad to do this every once in a while so they dont crap in their tanks lol? im sure it would prolong the time before changing substrate and it wouldn't smell as bad in the tank but im wondering if this would be bad for him

I don't see why putting him in water would harm him. Just make sure he's not totally submersed. :D

just make sure that the water is luke warm

As long as you're spot cleaning the feces as you see it I don't see why you'd have to change the bedding more often.
I only do it once every several months unless the snake manages to completely obliterate the tank some how.
Just keep in mind that you do run the risk of stressing out your snake because some of them absolutly hate to go swimming.