Honestly, I've seen some VERY good uses of Segways (Most obviously one used by a physically disabled person in place of a wheelchair, which is just a beautiful use of technology)
I also wouldn't use one myself, not because it's dorky but because I already have a system built in for movement over regular distances. Feet. I LOVE walking and I for one am happy to walk all day if I can. Which is the problem, as the best market for normal sales would be people in walking friendly places.
'cep people just walk.
The place where I live has a family that each have them, We'll see them go into our town center with them, and all I can ever think is... Why not just walk? What's the rush?