I think that blue could be fine, as long as the complementing body color goes well with it. It's especially important in LBCs, as they are open cars and the interior and exterior are visible at the same time. Two shades of blue could be very nice.
I see cars for sale frequently that have bad color combinations, and they just don't sell. An extreme example was the purple midget with a beige interior that was discussed here quite a bit.
Of course, practicality is an important consideration. White interiors, for example, look nice (for a while) but aren't terribly practical. Things that don't show dirt are worth considering seriously, especially in a car open to the atmosphere a lot.
Anyway, most important is good taste. If you're like me, and have no color sense, there are plenty of people around who do have it. Doesn't have to be (and probably shouldn't be) a car expert.