Worst guns...
Technologically...
The Japanese Type 94 pistol. Oh what a nightmare this thing was, from its horribly shaped grips to the sear release running on the OUTSIDE of the slide (could be fired by simply grabbing the slide wrong).
The steel was so soft that it would batter itself to death, even with the wimpy round it fired.
Luckily, it never made it into general circulation.
Worst high price guns? Just about anything by AMT. For the price they charge these guns should be great. I've yet to find one that is 100% reliable, and I've used a LOT of them.
Worst gun to clean (also a separate thread)?
Tie between the Desert Eagle, the AMT Backup, and the S&W 2000 series .22s.
Worst lineup? Remember the old Grendles? Horrible, horrible guns.
Interestingly, in opposition to someone's post here, my Polish Radom is a dream. Yeah, it's rough & crude looking. But it feeds and functions 100%, even hollowpoints, it is accurate as stink, and the trigger isn't all that bad.