According to the following article, there may be some false positives with bedbug sniffing dogs:
I think the dogs can be part of a bedbug control strategy, but not the only thing to indicate the presence of bedbugs. I would never make someone pay thousands of dollars just because the dog indicated the possibility of bedbugs. Nothing replaces a complete and thorough inspection. These insects are not microscopic and their droppings are not hard to find.