It really never ceases to amaze me. Perfectly rational people, most of whom would never consider having their barber do their heart surgery (or their surgeon do their hair, for that matter), have no problem rendering judgement on the validity of complex scientific theories. In an earlier post, I mentioned an example of this happeining with evolution. At the moment, another example of this sort of thing can be found in the comments section of a recent post that mentioned Einstein.
Personally, I'd be the first to say that there are things in relativity that sound silly to me. They sounded silly to a lot of physicists when the theory was first published, too. Yet relativity was accepted fairly quickly by most physicists. It might be that relativity is wrong, and if so, I expect that we'll find that out someday. At the moment, however, a hell of a lot of physicists who understand the math and the experiments that have gone into establishing relativity think that it's a pretty good explanation of the way things work. That's good enough for me.
I still don't understand why this doesn't work for everyone.