Why are Llama, Astra, and Star linked together? They hardly deserve to be.
Worst Revolver- My first gun, a Taurus Model 83, in nickel. Bad rifling, uneven face of cylinder, and bad timing. Soon sold after I bought a Dan Wesson Model 15-2, a great gun. I haven't had a single bad revolver since.
Worst Semiautos- There's a bunch. AMT Back-Up 380, insanely hard trigger pull when new, off the gunsmith's scale. Came back from AMT with a slightly better pull. After the local gunsmith worked on it, he said, "It hasn't got one single smooth part inside it". The AMT Hardballer Longslide I had was a jam-O-matic that looked great, but was totally unreliable. My FTL "Auto-Nine" blew the extractor off on the first shot, and again after being fixed used THE EXACT ammo called for in the manual.
The Colt Commander I had was really pretty, until Colt's service dept got hold of it, and scratched it all up. They didn't fix it. It had all kinds of issues, most of them due to not one part of the frame or slide was straight. My S&W 4506 had all kinds of issues, it would hang up just short of going into battery, so a stronger spring was put in, and it helped, a little. It had "limp wristing" issues if not held with a death grip. What a dissapointment. I've had a few other guns with "limp wristing" issues, and they were either fixed, or I got rid of them as fast as I could. I won't own one.
I have never had an issue with any of the four Astras I owned (I still have 3, two A-75's, in .40 and 9mm, and an A-100 9mm), they all shot great. My Star 30 was one I wish I had never sold, it was fantastic. All my Dan Wesson revolvers have been pretty much totally trouble free, and my EAA Witness .45 is one of my favorites ever. Almost all the problems I've had have been with brand new guns, the used ones have pretty much been great.