When a dog is being house trained.. they are taught peeing inside the house is bad. Dogs aren't stupid. They know when they do something bad, you will pay attention to them. When somethings wrong with them, they don't care if it's bad attention or good, they will do things to get your attention.
Vets go through 4 years of general science courses, then another 4-6 years. They do more than that to specialize in an area/on a species. So 2 vets plus a specialist.. that's about 30+ years of formal training plus however long they had were on the job for. How many years of formal training have you had, to be saying that 3 vets are wrong and there's no way it's true?
In general, I would NEVER rule something out on a forum like this, unless its completely obviously, common knowledge, now what it wrong or normal. People may take you (in general.. not "you" personally) to heart and not go to the vet if they don't think it's very serious or anything. Until I have had formal training, I would state my mind if I don't think something is correct, but not go out and say "it is not..." Actually, even after I get the training, I probably would never say that on a forum. Because if I decided to rule something out, so the owner did not get the help the pet possibly needed, and it was what I said it wasn't, I would feel horrible. On a forum like this, you just don't know enough about the dog itself, its medical history,etc. I may be the only one who thinks like that but.. yah.