Originally, the character of Snuffleupagus only ever interacted with Big Bird. He'd always come and go when no one else was around, and consequently no one ever believed Big Bird when he told them of his existence. The producers decided to reveal him to the other characters partially because they felt it was sending a bad message to children that adults will not believe them if they have something important to tell them. See more
Oscar the Grouch
Aw, how's that for disgusting? If I watch anymore of this hugging, I'm gonna get sick to my stomach! Let's get out of here! But first, I've got to say that this revolting spectacle was brought to you by the letters J and S and by the number 6. And Sesame Street is a production of the Children's Television Workshop. Hey, come on. I'll meet you down at the swamp. Heh heh.