It depends.
Large cages once every week, unless there are more than one hamster, then every other day.
Small cages every other day, and there should only be one hamster in a small cage.
If the hamster is in mating season you might want to clean them out more often, as the smell is worse and they urinate more.
Also, bigger hamster will urinate more, keep that in mind. :)
1-2 times a week. mine doesnt really smell up the joint so that's my routine ;D
I recommend that you give it a bath and a shampoo (but carefully, so you do not drown it).
chinchillas take dust bath because that is how they wash themselves also because they live in mountains and that's the only thing they have to wash themselves with. :D
dog?
once a month
Every day is common hygiene.
every day or night
every single week
Once a week.
ONE
You should give them a bath at least once a week. Well at least that's what I did with my beagle Cassy.
1 or 2 times a week
every other day