Smelly Dog?

Our dog is so sweet, except the way she smells. A friend suggested it's what we feed her (Purina, small bites) she's a small dog, (PBGV - Petitie Bet Griffon Van Deen) and she's got a wonderful temperment. I brush her teeth about once a month and I use "doggie wipes" in between her baths (usually bath her ever yother month, as I don't want to dry her out) she has long hair, doesn't shed and is hypoalergenic. Any good ideas? Do you think it's what she's eating? Should I be giving her supplements?