For me, it's the folks who claim that even the slightest amount of damage to a helmet indicates a "save" from severe injury or death. There was one gal in particular who frequented the SoCal forum and was convinced her helmet saved her life because, after a fall, she found a pebble embedded in the foam. "Imagine how much force that took!!!" was her story. She seemed like a nice-enough person, so I refrained from pointing out that I could stick a pebble into foam with finger pressure but don't have nearly enough strength to force one into my skull.
Folks seem to think bike helmets have almost magical life-saving properties.