My worst pistol should not have been a bad pistol. It was a Norinco 213 with both 9mm and 7.62 barrels. This was a proven design and China can make reliable firearms. The problem was the safety, not part of the original design, was so loose it would move randomly while firing.
I know what you mean.... the original Tokarev design only had a simple half cock safety. To be imported these guns had to have a manual safety installed, these Chinese ones were hastily thought up and were total junk. Really messed up a simple, reliable design. Later imports from Russia, Poland and Romania had similar cocked up safeties installed. I removed the add on safety from a couple guns, plugged the holes and just went with the original half cock when I carried one around the farm.
As to picking my own worst gun that's a hard one to narrow down. I've bought a few that were not very accurate no matter what I tried, a couple semi-autos that didn't feed reliably but were fixed by a new magazine. Did have a Taurus and a Llama (both in 9mm) that shot incredibly low (fixed sights) and would only shoot to the sights with 147gr ammo. Filing down the front sights on either was out, would have filed down to the slide to get them on target.