This is my problem, my 2.5 year old yorkie has wavey hair and my 1 year old was long silky hair, if I don't bath them

twice a week they look nasty, and I was reading in a magazine this weekend I'm not subpost to bath more then once a month. THey hate that inbetween spray stuff. Got any ideas... I have tried everything that Petsmart has and don't like any of that.. Please help