You see all those Jags and Benzes and Beamers on the road and you know there are a hell of a lot of rich folk in South Florida, but until you've been to Three Dog Bakery, you don't know the half of it. Some of these people's dogs eat better than the average middle-class American kid, let alone a starving tot in the Third World. They don't sell doggy biscuits, they sell doggy biscotti. The place sells bagels (they call them "Beagle Bagels" and "Springer Spaniel Sprinkles") and carob cookies ("Dottie Spots") and birthday and wedding cakes. When, you ask, could a dog possibly need a wedding cake? Just before one of these prime, AKC-registered purebred studs gets down to making pups with an equally well bred, handpicked bride, that's when. These people actually hold wedding ceremonies before the consummation. In addition to these doggy baked goods, the place sells its own brands of dog food. Or more like dog cuisine. One brand is made of white meat-only chicken and goes for $30 a bag. Another brand is for the upscale, sophisticated, vegetarian dog and contains real spinach and Parmesan cheese. Hard to stomach all this? Make like Fifi and eat some grass.