I think that considering the popularity and success of Sesame Street today, it's hard to believe when it first came out they expected it to last only a couple of seasons.
Just the other day I bought a plushie of Mr. Snuffleupagus. When Snuffy first appeared on Sesame Street he looked just plain horrifying! And Big Bird was pretty homely too in his early appearances. Not to mention really dumb. And Oscar the Grouch was orange. The Count was much more spooky and sinister, with hypnotic vampire powers and a much more evil-sounding laugh. They thought that made him too scary for little kids so they softened him up. And Grover was a very dark green, almost black color and he was also more creepy-looking. When he was changed into the lovable furry blue version we know now, the "old" Grover once made a brief appearance - as Grover's mommy.