We have been bathing Copper once every two weeks. I know it maybe too often but, he does gets really smelly! He is outside a lot and gets into everything. A couple weeks back, he was eating salmon eggs streamside. ;D
Only when he needs it ... not that often, usually precedes a roll in something undesirable -last week it was a bag of rotten fish he encountered on a woods road - not his fault that some yahoo with no respect for the environment and its inhabitants would throw that out of their truck -gross!!! He smells pretty good most of the time. And i use wet shampoo, Johnson's baby shampoo mostly.
Kobi has had one bath... he is going to be 19 weeks I believe tomorrow. The only reason for the bath was that he had two in the cage accidents and smelled a bit like pee. I used nothing but water and it seems to have done the trick.
I'm with gunnr and kian; we don't bathe unless she needs it. If she smells bad after day care, the smell just seems to dissipate on its own and she smells sweet within an hour or too (I know because I kiss her on the head all the time). She cleans herself like a cat.