The Keeley compressor & box I bought a few years back from someone on Ebay arrived absolutely hum-dinging of smoke. Like the previous owner had kept it in his studio, smoking 20 a day with no windows.
I gave him neutral feedback as this is something I
expect to be mentioned, or at least I would have expected the item to have been aired-out. Had I known, I would have concentrated on other auctions. Smoke has a horrendous affect on electronic equipment.
When we're talking boutique expensive guitars & amplifiers, having some assurance that the item has been well looked after goes a long way for me. I expect a seller to tell the truth. If something is well-used & regularly gigged then it absolutely changes the price. Simple as that. If the power tubes on an amp have been thrashed, It might need a re-tube. Re-tubes aren't peanuts.
What people choose to do with their stuff is totally up to them. I don't get to pump the master on my VH4 above 9 o clock & it's a stadium-worthy back-line, arguably wasted on a, now, non-gigging recreational musician. That along with some custom guitars & pedals amounts to many thousands of pounds & dollars.
I play my guitar a lot, but I make an effort to look after them. Might have to start putting them back in the case once my daughter arrives though!