I nominate the East German Pouva Start. I had five, believe it or not, and none of them worked for longer than two rolls.
They either had haze (almost non-repairable because the elements are glued in or held with crappy circlips, once out, never back in), the shutter would bounce back open, the finders broke or fell of and one died slipping out of my slippery, sweaty summer hands. The camera, being made of bakelite, did not fare well.
Some of the have metal clips on the feed roll side which scratch the film.
I finally gave up and never had the urge to get one again.
When it did work, it produced great images, was super light and the finder, provided it is clean, is very useable, even for a glasses wearer.
There were just too many downsides.