I've been the KOM on a few climbs. Most of the time I've created my own segment where others haven't ridden yet. I tend to lose my KOM pretty quickly once the word gets out. Here's one of my favorites. At about the 0.15 mile mark there's a series of 170° switchbacks on a narrow bike path. Even going up hill it's difficult to not fly off into the grass.

http://app.strava.com/segments/2159043

However I once got a KOM and didn't even realize it until after I'd uploaded my Garmin.