I recently tried to be a good samaritan to a friend at work, an immigrant from China who has commuted on a Northrock (e.g. Costco) hybrid as long as I've known him. His bike is always parked in the same corner of the parking lot; one day I went in for a closer look, and I found the cables dangling loose, the handlebars installed backwards (twist grips and brakes on the wrong sides; index numbers on the grip shifts upside down, but at least the brake levers rotated forwards!). He's been riding SS in the DR slack small/small combination for as long as he can remember.

I arranged with him to ride it home, clean it up, and ride it back. No charge, I really just couldn't stand to see his bike in that condition! When I got it home (and took some time to massage my wrists, which were dying from riding on reversed handlebars!! OUCH!) and took the back wheel off to clean some grime off, it fell apart, ball bearings all over the place. Turns out he had a broken axle and didn't even know it, the QR is holding it all together.

I packed it back together again with some fresh grease and the QR holding it together, flipped the bars, hooked up cables, and brought it back to (in a car, I didn't ride it again) with a severe warning about his broken axle and that eventually his QR will break and his rear wheel fall off while riding, putting his life in danger. I told him also if he went to a bike shop, they would probably pressure him into buying a much more expensive new bike. He was appropriately scared, and decided instead to just buy another whole bike. That one cost him $200, he's used it for X years, so he's ready to dispose of it and buy a new one. I told him I'd give him $40 for the old bike as-is, for parts.

A few weeks went by, and he came and told me he hasn't bought a new bike yet, but he finally took the old one for a ride -- "It's so much better! I love it!" He's not worried; he rides slowly and only on the sidewalk, not the street, so he doesn't care about the broken axle and impending wheel failure.