Well Bob, children in general love to be tickled within reason. They like the laughter, the loss of control, and the close attention. That is when it's done within reason.
Always being a marshmallow of a chick, I was the recipient of more tickle attacks than I ever wanted. I'm actually surprised that I ended up being a ticklephile because I hated it as a kid. It was usually abusive in nature or to settle someone's pathetic curiosity (is the fat kid really ticklish?). I was finally introduced to it in a way that was gentle, fun, private, and even sensual (without it being sexual). I was paid special attention, just the two of us without public displays that were usually embarrassing. Needless to say, I learned to find it fun and enjoyable; it was introduced to me many years before I discovered the sexual aspects.
So in answer to your initial question, I don't think the Elmo doll has any negative connotation to it with the exception that it's just an annoying toy to me.
