There are many different definitions and signs of "cults" as there are religions. It seems to be a rather loaded word that get people on the defense or offense pretty quickly.
Even Jesus started what some would consider (and some considered at that time) a cult.
No one would argue that Witnesses are an unhealthy, high conrol religious group, though. (Except Witnesses, of course.) And they do fit the profile of some definitions of a cult, but not all.