It depends what you grow. The little reds like Foch, Marquette, Oberlin/Pinot Noir....the birds strip them quickly. But my big whites (Cayuga) and table grapes are never bothered....too big.I have yet to have a problem with birds other than an occasional nest in the vines.
As far as I know it's nothing to do with the smell but the anthocyanins that appear in red grapes during veraison. This also means green grapes should not be affected by birds as far as my understanding goes. Same as with white strawberries.As the grapes go thru verasion the smell changes and attracts birds. Netting is virtually the only best defense. Even with netting, which will only last 3-4 years the birds sit on top and poke thru getting what they can. They will search out weaknesses and exploit them.