All I can tell you is that I cache in one of the areas Alamogul hangs out, I've run into him a few times, and I've seen his signature in many logs. In four years, I've never once seen anything to make me think he has or would even consider logging caches he hasn't actually found. When you see the man in action, it's easy to believe he's found 100,000.
I have also seen his stamp in logs, but it seems like some people say there may be a question as to whether one man did all the stamping.