I'm in no shape to be passing roadies, and I ride my MTB with knobby tires and pull two kids in a trailer, but the other day I was going faster than normal, maintaining 15-16mph or so and saw two recumbent trikes on the trail ahead of me, tracked them down and passed when I could. Payed for it later though when I hit the hilly portion of the ride a 70 year old guy passed me no sweat. Kudos to him, I think he's passed me before too.

I don't see any problem with someone using passing someone as some motivation to kick it up a gear as long as they're staying safe. Some of the unsafe stuff people here have seen is just stupid. I like the other stories here though.