You are right, food companies pay for studies.. but they study so they can improve as well. I don't really pay attention to studies paid for by a financially interested party though... just the ones released via news letter directly to veterinarians by reputable researchers, who are often retired veterinarians themselves.
Research does not always come with an inclusion regarding the source of funding, and research is expensive. Who do you think is gonna cough up the bucks, if not a financially interested party? This is why there is no (or practically no) research directly comparing commercial kibbled diets to raw... there are no corporate entities with the kind of financial resources it would take to fund such studies except the entities which manufacture kibble, and they certainly ain't gonna go there.
As for retired vets... the ones I know buy a retirement home, sometimes, or travel... many of them go fishing a lot, or miss their former lives and go back to work a couple of days a week for a veterinarian friend. The proper design of research studies is not a skill developed either in veterinary school or during their career practicing medicine. I would be very surprised if there was a significant number of retired veterinarians doing research.
This study is interesting: Perceptions, practices, and consequences associated with foodborne pathogens and the feeding of raw meat to dogs
. Basically, it says that they might have found some stuff, but that they couldn't attribute this to that, and couldn't really draw conclusions. It ends with "In addition to veterinary consultation, development and dissemination of credible literature about the health implications of various pet diets, especially in media perused by those choosing alternative diets for their dogs (such as the Internet, newspapers, magazines, and books), would be helpful in order to provide science-based information to pet owners, so that they are able to make better informed decisions. However, because of the affective and ideological components involved in the choice to feed raw meat, even the most comprehensive scientific review will not persuade all owners to change their feeding practices." I would suggest that methods for persuading owners to change their feeding prectices was the whole point of the study. It was paid for by Purina.