My all-time POS is a Charter Arms AR7. I bought it for a car gun and it was ok when I first bought it. However weird self inflicted stuff just keeps happening to it. After a month or so the front site decided not to stay in the dovetail. I sent it back and this is the factory repair I got back. Now that is some fine craftsmanship there.
Next the front of the magazine well fell off (while it was stored inside the stock). This is kinda important because with this piece is what prevents the magazine from moving forward during firing. If this happens operation is just a bit impared. The receiver is made of cast zinc, so there is no practical way to repair it (super glue and epoxy were useless). The gun can be fired, you just have hold the magazine in place.
After that happened I just tossed it in the back of the gun safe. A few years ago I noticed that there is some kind of evil chemical reaction going on inside the stock. It is bubbling up like there is something hot in there, I have no idea what is really going on in there and to be honest I don't really want to know. It is hard to photograph, but here is one of the bumps in profile.