Way to revive a 2006 thread! 🙂 I think it's an interesting question and that the answer is it's both hard and one of the best, for a lot of reasons people have touched upon.
I'm going to take away the question of being creepy or whatever for the sake of my exploration because, yes, obviously as mentioned above with the George Clooney example, the way you approach others and the way you engage in your fetish will make a huge difference always.
I think what's hard about it—particularly if you're a ler—is that there are a lot of people who do either find tickling triggering, unbearable, or completely nonsexual. My sense is there are a lot of categories of "not into it / hard limit": 1) people who are insanely ticklish and/or hate it (often these people have had their boundaries crossed with tickling which is what makes them hate it/negatively associate it), 2) people who associate it with childhood / their family, and just can't imagine it being a sexual thing, or don't want to because of their aforementioned associations, 3) people who it just "does nothing for" — now certainly if this kind of person is open, they might be able to get into it to some extent because it turns the partner on, but again it depends on their willingness and openmindedness.
I agree with what some others have said here, though — that in some sense, it's really one of the best fetishes one could possibly be blessed with, especially given some of the other (no shame, but IMO) rather disgusting or more-likely-to-be-offputting things people are into. Because tickling is generally considered playful and flirtatious, it 1) can be very easy to integrate into a relationship, even before you reveal your fetish/kink, 2) can potentially be adopted by a partner who has some tendency toward BDSM/kink, 3) can be easily indulged in playfully with friends etc without disclosing that it's a fetish/kink for you*, 4) there's a wealth of both playful and hardcore tickling videos and stories online that are very easily discovered/enjoyed.
Personally I've never been in a relationship with someone who was into tickling and everyone I've been in a relationship with has embraced it to some extent — even though a few have fallen deep into the "insanely ticklish/hate it" category and have had limited capacity to allow it (which, personally, is both frustrating and really exciting/hot in a certain way too).
*This is, of course, an ethical question — whether, for example, playfully tickling friends when it's a kink for you and they don't know that is ethical. But that's another post for another time. My general feeling is it's innocent enough.