If the other dog has a suppressed immune system or some underlying problem, then perhaps a raw-fed dog can make another dog sick. But keep in mind the inordinate amount of bacteria dogs usually ingest anyway, not to mention the plaques of bacteria covering the teeth and gums of the kibble-fed dogs. People recall raw-fed dogs being the only dogs at dog shows that did not get sick with some communicable disease of some sort, and then instantly assume that it was those dogs that got all the other dogs sick. A more plausible explanation is that the raw-fed dogs have a much stronger immune system and are thus better equipped to fight off diseases and "canine common colds" that circulate at shows (and possibly that they have been vaccinated less than their kibble-fed counterparts, which results in a stronger immune system). For a more in-depth discussion of how processed foods suppress the immune system, please refer to Raw Meaty Bones.

Just some final thoughts on bacteria and raw: this is what finds its way into the "sterile" kibbled commercial foods:

"Meat products not intended for human consumption, such as inedible tissues, condemned portions of carcasses, and entire carcasses of condemned animals (eg, animals found to be dead, dying, disabled, or diseased at the time of slaughter), are also used for dog food. Because of the inherent nature of these products and the less stringent handling requirements, compared with products approved for human consumption, these products may contain high levels of bacterial contamination." (LeJuene, J.T. and D.D. Hancock. 2001. Public health concerns associated with feeding raw meat diets to dogs. Journal of the American Veterinary Medical Association, 219(9): 1222.)

 And as for commercial foods being "bacteria free" (an assumption that is often inferred when people put down raw diets because of the bacteria):

"Pet foods, commercial or homemade, provide an ideal environment for bacterial proliferation." (LeJuene, J.T. and D.D. Hancock. 2001. Public health concerns associated with feeding raw meat diets to dogs. Journal of the American Veterinary Medical Association, 219(9): 1224.)

So do not be fooled into thinking kibbled, commercial pet food is a sterile, bacteria-free source of food! The starches, rancid fats, and sugars in kibbled foods provide much better food sources for bacteria than the proteins in raw meat.