Dog psychologists, or dog "communicators"?
I do think a lot of dogs could benefit from a visit to a doggy "shrink" that can analyze their behavior, and help owners figure out what is going on with their dog. However, I tend to call those people "Behaviorists".
Animal communicators? I'm really not sure.. I don't believe any of these people like that pet psychic lady are able to deeply communicate with animals. I think their motivation for making such claims is to get a lot of attention and money.
Who knows, though, people we've never seen or heard of might actually HAVE that ability. You can't really accurately say that nobody can, unless you've met everybody in the world.