As said, people fear high mileage, fullstop. A small exception can be made for bikes that are advertized as highly reliable (even if they're not) rather than, for instance, fun. High mileage on a Honda ST1300 for instance, doesn't really scare anyone. A 1200GS is said to just have been run in after 30.000 miles. Unless the bike is famous for being an exception, people fear the miles.
Doesn't help that the big KTM's started off slightly unreliable, with waterpump issues and sidestands causing expensive engine rebuilds. The engines themselves are fairly bombproof when maintained well, but the damage was done a long time ago.
Not necessarily a bother, I just buy older bikes for cheap as no one else wants them for silly reasons :P
If you can't fix it with a hammer, you've got an electrical problem.