Totally agree!!
Even what he says, attractive or not, if it turns out that his tips lose most of the time, it just reflects that what he says is either irrelevant or incorrect.
Is there any value that he still exists in the horse circle? I don't think so.
For your first question, I think my method still works. You give him $500~1000 for him to bet, if after 3 seasons (totally 1500~3000 capital), he lost all of it, then he's just rubbish.
If he can improve, he can restart his tips next season.