Where you list your equipment for sale makes a big difference. Post on FB marketplace, craigslist everyone should expect lowball offers, random questions etc.. The more general the site, the more mass appeal of it the bigger the more likely you get these types of questions.
It's so easy to simply message someone with a question versus going through multiple google results, watching a 10 minute youtube video or ready a review. Why do all of that when it only takes a few seconds to message the seller is unfortunately the mindset of many people regardless of age.
Personally I only sell my gear at a handful of places. KEH/MPB my local camera store, or FredMiranda forums which is where I tend to get the best money for my equipment and almost none of the hassle.