Having a white coated breed we really over did it with bathing to start with. Dirt was like a magnet and bathing seemed the only option, we were told we were over doing it thats why he was getting so dirty, didn't make a lot of sense to me but we stopped and they were right.... dirt doesn't seem to stick anymore and he looks whiter than ever. We're finally letting his own oils do what they are supposed to do
Fortunately Dalmatians don't tend to have that doggy smell so that isn't an issue.
So I'd defo say only when absolutely neccersary unless you are going to show etc