I'm not sure what it is... this one just seems to miss the cutting-edge Seinfeld humor most episodes usually have. One particular detractor from this is the flamboyantly gay wigmaster who is staying with George and Susan - unbelievably cliche that his character seems to destroy every scene he's in. None of the four main characters have any particularly great lines in this one - except for Kramer's interaction with the cop at the end of episode. The whole Kramer-as-a-pimp bit was overplayed. Coming from Spike Feresten, I'm suprised he couldn't have handled this episode better.
Case in point, avoid it.