I have never had anyone ask about my watch(es), BUT I have had various folk ask inappropriate questions about other things.
A rather irritating neighbor who has no qualms about getting personal with others in our neighborhood about anything asked how much do I get from Social Security.
Others have asked how much did my house and car cost.
Another asked how much was my yearly salary when I was working for a large defense contractor.
A "former" mere acquaintance asked what my pension was.
I met those questions with a "glaring drop-dead stare through the back of the head" response, and none of those folk asked me a second time. The stare seems to have made them uncomfortable (its intent.)
On one occasion though, a very nosy (and inept, he was a foreigner and had poor English) refrigerator repairman asked me twice what was in the two huge safes in my dining room. Between his ineptness (pounding inexplicably and unsuccessfully like hell to try to release the ice-maker panel in the fridge) and his repetitive question, I totally lost it.
I responded that what was in the safes was the formula for getting him fired for sticking his %^#[email protected]*&! nose where it did not belong. Then I told him (almost shouting) to pack up his sh__ and get the "F" out of my house. He very quickly and quietly packed and left; he could not get out of there fast enough. He obviously knew he had made a VERY bad mistake.
That was immediately followed up with a nasty phone call to the company to find his manager with whom I had a very serious talk. The manager was informed that if any burglars ever presented themselves, I would be pointing detectives right to their company as that repairman from their company would give me cause to suspect something to do with the crime. THAT really unnerved the manager, who became more than extremely apologetic. He said nothing like this had ever happened in all the years he had employees and was disturbed to learn of what had just happened.
Don't know if the guy was fired, but I like to assume that at least his experience with me would cause him to keep his big fat nosy mouth shut in the future.
The best way to deal with these brainless nosy no-boundaries idiots is to not respond if possible. The "dead stare" also seems to help in making them re-assess what they just said.