From a internet buyer’s perspective, keep your life real simple and don’t read too much into it....It should be a 0, 1 scenario. NEW or USED, that’s all there is.....Don’t fall for the "hardly used, less than a 100 hours, took out for pics only", meow, meow crap. You could read into it as dude's a relatively more desperate seller and bargain more.
If you are visiting with a guy in person to buy some gear, you can infer a lot more now by looking at his room size, choice of music, how much gear he has, etc.
a) If he has a lot of different types of gear, multiple speakers, etc (i.e. gearhead), there is a higher probability that it may have been lightly used (in case it wasn’t his favorite item).
b) Take a glance at his music collection and have him play something. If you get the feeling that he listens to Diana Krall at 60db, he may not have beaten drivers to death. If he’s playing Pantera at 95db, he could have beaten drivers to death.
c) Younger hometheater guys can beat the living daylights out of subwoofers. Be careful buying subwoofers from those dudes. Older audiophiles with "fuller range" speakers could have tried a sub and could have kept it turned off a lot, etc, etc
d) Tube dudes will generally lie about how much usage the tubes had unless you can see that he has many different tube amps or other exquisite sounding SS amps. There is a higher probability that he may have used it less in the latter instance.
e) If ex-wife is selling divorced dude’s gear, you could hit a gold mine w.r.t prices (as she may be selling it at the fake price the dude told her it costed 😁)
etc, etc, etc
Use some common sense, in general.