I love the OT, but season 3 had some duds. I'm thinking of two in particular: "New York's Shiniest," and "The Case of the Hot Kimono."
First, New York's Shiniest; this was some corny, cliched sci-fi cop type plot. One thing about it that I found especially weird was the carousel scene. Two of the turtles are being pursued by a robot, so their choice of defense is...to jump on a carousel and start riding it...the robot jumps on and lands on its face and doesn't even attempt to get up...once the carousel has completed a full circle, the turtles jump off and the robot that was chasing them a moment ago has disappeared...Yep! If someone is ever chasing me, all I have to do is lure them onto a carousel and they'll disappear!

Then there's the Case of the Hot Kimono: I just think an entire episode dedicated to recovering stolen laundry is epic lamesauce.