Hello, If your house smells like dog, it's probably a combination of the presence of your actual dog and the things the dog leaves behind in the house. In many older, non-altered, or less house-trained dogs (and, incidentally, frequently in cats) house soiling could be a problem that the owner doesn't realize exists. Is your pet healthy? Could he be urinating in the house when you leave home? This is the first thing to look for, as it would give a smell to your home that would be unpleasant and hard to locate.
I don't recommend washing your dog more than once a month, but you should consult your veterinarian about your dog's individual needs. For example, some dogs have allergies or sensitive skin and cannot be washed as frequently, whereas some dogs, especially large breeds that go out hiking/swimming/camping, need baths with a mild shampoo more frequently to keep the skin healthy and free of debris or parasites. If your dog itself doesn't smell bad, and if he's healthy and happy, I wouldn't adjust your grooming habits.
Finally, take on the house. Do you have carpets? If they're covered with hair, they will smell like dog. Some people go "nose blind" to the dog smell after awhile because they're so used to it- frequent vacuuming of any floors should help. Having a wet dog on your fabric surfaces will create a lasting smell, as will, of course, a dog with anal sac problems (consult a veterinarian if this is the case). If all else fails, steam clean the carpets.
With a clean dog and frequently cleaned floors, you'll get that odor under control in no time!