Putting a watch for sale is for me an uneasy experience, I want everything to be right and I probably shake at least as much as the final buyer until the watch reaches him and he's happy with it.
Another bothering aspect is annoying prospective buyers. The insecure, the lazy, the brazen, self-entitled folk who think they're buying on amazon or who simply think they're smarter than everyone else. I'll start off with a couple of examples and hope you can share your experiences as well, so maybe some of those buyers will read this and learn a bit about "buying etiquette".
Those who...
You put a watch for sale for, say 630$, shipping included. You even post "open to reasonable offers". You receive a PM: "I'm taking it for 500 now". You either ignore the buyer or answer "what did you drink?" or even "F*** off". The prospective buyer reports you for being "rude".
Those who....
You put a ZF 15500 for sale. You receive a PM: "What's the difference between ZF and APSF of this model? Which one is more gen-like in terms of dial color? How is the quality of the case finishing? Will someone recognize it's a fake watch?".
Those who...
You sell a diving watch. Buyer receives it and sends you a PM: "The watch doesn't work! It will only run for a couple of hours and the small wheel can't be pulled, it's stuck!". You answer: "Did you perchance unscrew the SCREW-DOWN crown?". Answer: "The what?"
Please share your experiences, I'm sure there's more annoying and hilarious anecdotes to tell.