The Professor Hastings sketch I remember seeing was "What's My Part? - The Foot." He won the game by accident when he said that his foot fell asleep. It was a 1969 game show sketch featuring Guy Smiley. According to MuppetWiki, The skit was last seen on episode #2621 (Season 21).
I don't think I've ever seen that one. Maybe it wasn't heavily in rotation. I stand by my main point though, the character was quickly abandoned in the 70's. He's not as well remembered as say, Don Music, Guy Smiley, and Sherlock Hemlock, all who had been featured heavily, even in rerun segments through the 90's.
Oh wow, I had no idea! About Wolfgang, that is. I haven't seen him on the show for *years*, so it's good to see that he's making an appearence every now and then.
He may not be referred to by name, but how many seals have been on Sesame Street? And it's not like he has a distinctive voice... he just barks. So anytime they have a seal, it's the same Wolfgang puppet. Until they build a new, different looking one.
Yet, Kingston came around recently, and actually was African American, an no one complained...Maybe he was typed as a stereotype cause of his deep voice and his purpleness?
I still don't see anything outside of the classroom that was so offensive that they had to abandon him. But that's the problem with adding diversity to a cast. No matter what you do to a character, some wiseguy's gonna whine that he's a stereotype one way or another, and then if you make him dull and a token character, they complain about him having no personality.