Here's a couple of good ones Iv'e just thought of. Since Herry was known for Breaking stuff back in the 70's. Lefty could have tried to sell something to Herry, and Herry could have ended up breaking it, and Herry could say something like "Gee, I don't want to buy this. It's broken!" and walk off. Then Ernie could walk by and Lefty could tell Ernie that it was a work of Art, a masterpiece, one of a kind, and Lefty would sell it to Ernie for a Nickle.
Another Intresting customer could be Forgetful Jones. Even though Forgetful joined the show shortly after Lefty was dropped, If they were on the show together it could have been an interesting set up. Lefty could try to trick Forgetful by trying to sell him a cowboy Hat Just like the one he had on. Forgetful would agree to buy it, and Lefty would get all excited that he made a sale. Then Forgetful would say "uhhhhh I forgot, I don't have a Nickel........" Then he'd take his Cowboy Hat off and say, "Say, could i give you this here hat, in exchange for that uhhhhhhhhhh........" Then he could look at the camera baffled and say to Lefty "Well Gee, would you look at that? Looks Like I already have a Hat like that" And Lefty starting to get nervous cause he thinks Forgetful is on to him says "Yeah ummm, looks like you do, well I must be going now" and before he gets a chance to walk away Forgetful could say "But ya know, I don't have a hat like that!" Pointing to Lefty's hat, then Forgetful would take Lefty's Hat off his head, and put it on, and Put his Cowboy Hat on Lefty's head. Forgetful could say something like "Pleasure doing business with you" and walk off, leaving Lefty standing there with Forgetful's Cowboy hat on, which would be slightly to big for him so it would be covering his eyes.