Ignore gun-maintenance advice at your own peril.
Some might brag about how their guns run better when they're dirty, but take it from the author — clean is better for self-defense.
It is not an understatement to say that in the study of armed self defense, almost all time and effort is devoted to the practice and study of the "how" and "with what." Seemingly endless drills are done, drawing and firing from various states of readiness and body positions.
When not doing this, then folks are busy evaluating the tools--firearms in particular--with which to successfully engage the "threat." I doubt that anyone has been immune from reading multiple articles with titles such as "Revolver versus Semi-Auto" and "9mm versus .45" and, of course, handgun reviews.
Also, in the last few decades we have quasi-legal works discussing both the real and hypothetical consequences of the use of deadly force. All these are well worth reading if for no other reason than to motivate you to think about the subject matter.
But one area often overlooked or one that is mentioned only in passing is one basic step which helps to ensure, as much as humanly and mechanically possible, that your self-defense arm works on demand. This step is to clean your handgun each time you shoot it and also to periodically clean, re-lubricate and change out ammunition if the gun is not fired for long periods of time.
A dirty gun does not, in my opinion, work as well as a properly cleaned and lubricated gun. Coming from an era of corrosive primers, aided by military training and abetted by my passion for all things "gun," I like to--and am almost compelled to--clean my guns after I shoot them. I also inspect my carry gun frequently and periodically clean those such as home-defense guns that are in fixed locations.
Over time, I've observed how this need to clean and inspect self-defense arms has waned among the general gun folks for some simple reasons. Ammunition is almost always non-corrosive these days (except for some currently imported military surplus) and quality self-defense ammo has case neck and primer sealant that is resistant (but not impervious) to water and lubricants.
Modern handguns are, by and large, well-constructed tools, and those made for self-defense are quite reliable, if not extraordinarily so, under very adverse conditions. Back in 1911 when the 1911 pistol was tested, 6,000 rounds was the reliability benchmark (which it passed). Now, a 20,000-round service life test is not out of the ordinary for military and law-enforcement acceptance.
Indeed, I know of a Glock Model 17 in 9x19mm that fired 350,000 rounds as an ammunition test pistol before being replaced. (Noteworthy: There was no information as to if or how often the gun was serviced.) Such tests done by gun makers have, of course, found their way into many a marketing and advertising campaign.
The unintended consequence of all this is creating a perception that modern handguns need little or no servicing--and therefore they get none. I've found this expressed time and again in comments made by otherwise pretty sharp gun handlers who say something to the effect of how long they have shot their Brand X gun without cleaning. One fellow told me how his 1911 would run only 500 rounds before malfunctioning, while his polymer and steel gun would go 2,000 rounds.
In fact, on more than one occasion while examining someone's gun for malfunctions, I've found screws loose or missing (on revolvers), parts gone or dislodged (right and left ambidextrous thumb safeties on a 1911), or caked-up extractors (semiautos generally) and dirty magazines to be the rule, not the exception.
Revolvers don't work well with missing screws, as a friend of mine discovered to his chagrin. While shooting an IDPA match with his Smith & Wesson Model 10, he went to reload and the cylinder and crane fell out of the frame. Why? Because the crane screw had loosened and fallen out. (Thoroughly cleaning the gun would have uncovered this before it became a problem, of course.)
I've also been told repeatedly how an individual's gun runs better "dirty." Funny, I wonder why this is not pointed out in any instruction manual, nor has any gun company taken advantage of this wisdom by shipping a gun all gunked up as a bonus incentive for the discerning customer.
As to the proper cleaning and lubricating, the accompanying instruction manual will often spell out just where the gun should be lubricated and where not. For example, the Glock pistol has a drain hole along the side of the cartridge pick-up rail that is not an oil fitting. Striker-fired guns must have their striker channel clean and dry, with no oil in them; otherwise gunk can and does retard the striker blow on the cartridge primer.
The "innards" of a revolver are close fitting, and too much oil, plus powder or pocket lint, can literally combine to gum up the action. A revolver can be loaded and the cylinder closed with threads or unburned powder beneath its extractor star, but it will either not cycle or will hard-cycle when the trigger is pulled.
In essence, the mark of a genuinely competent gun handler is not fancy grips on the most expensive handgun, nor an exotic belt and holster in which it rides. No, a well-maintained, clean and properly lubed handgun is the true badge of someone serious about personal self-defense.