Worst guest? Brent Spiner.
Worst idea for guests? Jonathan Frakes and Marina Sirtis, though I hardly blame *them* for the stinking pile of dogshit that was TATV. But it does make me feel better to hear that Frakes wouldn't have exactly been please if, say, AGT had been dominated by guest stars William Shatner, Leonard Nimoy, and DeForest Kelley. Which IMO would have been cool to see, but the TNG fans would have been just as pissed with that as I was with TATV.
And I agree with whoever said that any episode in which Shran and Trip could suck, that script? Totally out of the hands of the actors.