On C-Span this morning Brian Lamb was saying something about callers saying they're one thing (e.g. Repub.)and then it becomes obvious they're not what they say. I think he mentioned it's getting bad. I only caught the end of what he said so I'm not sure about the details but it sounds like the same thing Hannity is putting up with.
This is the defining tactic of DNC "seminar callers." However, in C-SPAN's case they deserve what they're getting, since they're the ones that intentionally split their phone lines by political party in order to control the debate.