I don't know if Setters have better noses. I do know that some dogs can smell better than others or it appears that way. Experience makes a big difference. When I am training dogs. I will turn lose a few inexperienced dogs through a course that I know has birds. I will normally get a few contacts with birds.Allot of times I will have to bring them back to an area were i feel confident that there are birds. It is allot of work to get these started dogs in birds, they miss allot.
Now, take the seasoned vets, run them through the same fields and come up with allot more birds. Why?
The seasoned dogs have a better nose? No,they can use it better,and have a better hunting pattern. The older, more experienced dogs alsopay more attention to diferent types of cover.