I laugh at most of what my vet says anyways, and your thoughts ring more true to me. I think in a dog with a white coat, they're going to be more prone to skin problems/allergies than say a double-coated, pigmented husky would, but that problem becomes aggravated when over-treated with steroids and topical creams and shampoos. Not to mention the antibiotics that can suppress immune systems and the horrible foods that most pet stores and veterinarians try to sell to their customers.
A breeder with a lot of information about dogo health that I've come across is Del Rio (http://delriodogos.tripod.com/), and I could be mistaken, but it seems like her dogs have thinner coats than the dogos I've seen in other pictures. She also has a lot of tips about how to deal with allergies. Does it seem like her dogs have skin problems from what you can see on the website?