I have three semi-auto pistols that are still in the evaluation/function-testing phase. One of them has fifty trouble-free rounds through it, and the other two have one minor failure-to-fully-feed, each, in their first hundred rounds. I do not yet carry/use these for defensive purposes.
I have a now-retired S&W Model 58 duty revolver that has gone "out of time," so that the hammer can fall before the cylinder has finished fully aligning with the barrel. It is still shoot-able, as the misalignment is very slight, but that is a terrible way to treat a handgun, as parts wear is accelerated. I could, however, load it, and still trust it to fire six times, if necessary.
All of my other handguns are trusted, to the degree that any mechanical device can be trusted. Most of these have never malfunctioned, or the cause of the malfunction was readily identifiable, and corrected. One example is a P229 duty pistol that I was shooting while in pain, during a mandated (police) tactical/low-light/"stress" high-round-count training class. I recognized the malfunctions as likely being induced by "limp-wrist" shooting, so finished the training day by using my other hand as the weapon hand. (Yes, it is good to be functionally ambidextrous!)
That P229 pistol has not malfunctioned since that day, but is now mostly retired, as I have switched to less-recoiling Glock 9mm duty pistols. (Glocks have a lower bore axis, and 9mm recoils less than .40 S&W.)
One morning, back in the Eighties, while unholstering after working a night shift on patrol, I discovered that the mainspring of my S&W Model 58 was rattling freely inside the grip frame, having snapped into two pieces. Parts breakage is always possible, even with weapons known for being reliable! (That mainspring had not been filed or otherwise modified, in a way that was apparent, but I had bought that revolver pre-owned, so the history of that spring was unknown.)
The memory of that broken mainspring has caused me to prefer carrying a second gun, or at least having one readily available, when feasible. The next broken part may occur in any of my weapons.
As for weapons I trust, these include, but are necessarily limited to: Glock G17, G19, and G34, SIG P229, Ruger GP100, SP101, and Speed Six, Les Baer Thunder Ranch Special, S&W Model 19, Seecamp LWS-32, and USFA Single Actions. (I do have more than one of some of the above.)