I have two. First came the Daisy VL rifle. To my knowledge, the only firearm ever available to the public to fire caseless ammunition. Made by Daisy, the BB gun folks, the propellant was ignited by air pressure. The ATF ruled that it was a firearm and not an airgun. Production ceased, ammunition became scarce or impossible to find. When you find it now, it's old, unreliable and expensive.
The second was a Para Ordnance 1911. I bought on previous reputation, the then (about 8 years ago) and current quality is not even close. MSH and trigger were plastic. The pistol had hammer follow after just a few boxes of ammo and customer service turned out to be extremely uncooperative. The disconnector was out of spec, protruding into the mag well. Why it didn't malfunction from the beginning, I don't know. I offered to send them the out of spec part, then they send me an in-spec replacement. Nope. They wanted me to send the whole pistol back, on my dime. Have had nothing good to say about Barely Ordnance since. Quality is gone, customer support is unreasonable.
I've bought and sold a lot of guns over the years that didn't turn out the way I initially envisioned. But they weren't "bad". They just didn't fill a niche I thought they might. That's my error in judgement, not the gun's fault. The two above, though, were stinkers by nature of the firearm itself.