i spend my time riding bikes, not cleaning them... i admit this may be more costly in the long run but think of all the time you save.

on my commuter (singlespeed) my drivetrain gets cleaned when i put on a new chain every six moths or so. other parts get replaced as they wear out (my bottom bracket is starting to creek when i replace it i'll probably clean the area around it thuroughly before chucking in a new one).

i never wipe down the frame.

my drivetrain seems smoother with a nice layer of crud and oil on the chain and gears... although i must say if i overlube i do clean the excess off sometimes but not often.

my commuter is pretty much designed as a bike i can just ride without messing with... sometimes that means getting ridden hard and put away wet.