Some are kiddie ties (you can tell by the lenght and the fact some are even clip-ons) but other (most) are for adults.
I own several Muppet/Sesame/Henson ties and wear them, and I'm not a kid (well not physically; I still am a kid at heart). I love "crazy" ties, they are great conversation starters and ways to express yourself while still being "dressed-up". I have tons of fun ties (including some of the Sesame ones on wildties.com). I have ties from Sesame Street to The Simpsons; and from Star Wars to Where's Waldo. Each tie is special and important to me (I won't wear just any "silly" tie). The image has to be meaningfull, and the Sesame ties really do that. I would love to get a Fraggle tie, (but sadly I don't think they exist). Although I "have to" wear a tie a lot, having Oscar and Slimey around my neck makes me able to stand it. Oh and if you are wondering, I do have some "normal" plain ties for those times when I need to be more serious and respectful (some people just don't appreciate a good Big Bird tie).