I've just got to share this one too. It didn't happen to me, but I was at least involved.
Last year I was at a local outdoor range on a nearly empty day. There was a gentleman a couple of booths down from me who seemed new to shooting judging by his stance and grip. After a few magazines, I decided to wander down and strike up a conversation during the ceasefire, which I enjoy doing with new and old shooters alike. He was at the range with a black Bersa Thunder 9mm.
After introducing myself and talking for a bit, he mentioned that he was having a lot of problems with jams. I moved a couple of booths down during the next firing section to watch and see if I could spot an obvious problem, which I didn't really; but he was still getting FTF's almost every round. Next cease fire I asked if he would like me to take a look at the weapon, to which he thankfully accepted. During my initial safety check, racking the slide felt INCREDIBLY gritty, and I noticed a marked resistance on the slide when slingshotting forward. I looked up at him and asked immediately, "When did you last clean this thing?"
"Clean it??"
"Never... why?"
We field strip it and just taking the components out my fingers are black with GSR. "Yup... that'll do it."
I didn't have time to show him to detail strip and clean everything like it needed, so I gave him the basics for future reference and the name of a local smith who would do damage control on how bad it was currently for cheap.
Had the thing for 4 years with no instruction, no pointers, no cleaning, and no one that offered any advice or help. His target didn't look too bad, but that weapon and his stance were atrocious. Literally 15 minutes and this guy is years ahead of where he was when he woke up that morning when it didn't matter how you stood and cleaning guns was completely unnecessary. I jump at those opportunities and love it when others do to. It's days like that where I'm proud to be part of this community.
~LT