Most vets will recommend bathing at most every 4-6 weeks with n approproiate pH shampoo for dogs, and preferably much less -- not more than every 3-4 months. It does strip oil from both their coat and their skin and can cause dermatitis (itchy, flaky skin is a common sign).
Needless to say groomers will say it is fine to bathe far more frequently but then that is how they make money... but remember even groomers tend to recommend every 6 weeks for a grooming.
It is far better to just wash dirt off with plain water -- really, shampoo and that whole rigamarole etc is rarely needed and if the dogs aren't left out they shouldn't smell... (well, they ARE dogs, and will smell like dogs :lol
. I only fully bathe my three when they roll in something unpleasant, which might be every 3-4 months or so, or for something really special (I will get Jaspar nice and clean and fluffy for the agility demo at Pet Expo next week!
). They stay really clean simply from going regularly to walk along the little stream in the Phoenix Park here -- if they get wet, even if they look realy dirty, it lifts the dirt and everything brushes out once they are dry. If I want them really clean, I take them to the beach as the damp and the coarse sand really gets their coats clean. They will look really grubby coming home --sandy and 'dirty' -- but they dry out (or you can rinse them in plain water) and they look fantastic when dry; the whites are really white from the abrading action of the sand.
Wipes are good for spot cleaning if you have a dog that tends to wee on feathering. Or just give the legs a rinse.
I think a lot of the people who see coat changes after neutering are actually in part seeing the result of too much bathing combined with shaving down or otherwise cutting their cavalier's coat (or the dog being overweight or genetically disposed as well, but once you neuter and oils drop a bit anyway, and if you are washing the dog every 2-4 weeks, you are really stripping out whatever natural oils remain. Conditiioner is NOT a subsitute for coat and skin oils, either!).
A dry coat isn't necessarily a problem for a dog, it just doesn't look as nice as a coat in great condition with its natural oils. Dry skin though can be very uncomfortable.