I have had three "worst shooting pistols/revolvers".
First one was an Astra Model 600 that could literally beat your hand into so much fleshy pulp if you went on firing it for more than 50 rounds. It may have seemed like a good idea at the time, but a straight blowback 9mm. is not fun to shoot.
Second was a Charter Arms Undercover that tried to disassemble itself during a trip to the range. Might have been the "hot" loads I was putting through it at the time: factory 148 gr. wadcutters. After half a box of these, the frame pins were nearly out of the frame, and the cylinder crane assembly was getting ready to fall off.
The third gun was a beautiful Browning Hi-Power, complete with a deep blued finish, ring hammer, and a trigger pull that was well into double figures. Add in a safety that was almost impossible to engage, tiny sights that couldn't be seen, and a slide to frame fit that was extremely loose, and you had all the ingredients for a gun that could hit the side of a barn. Maybe.