We are really getting caught in the tall weeds here.
The only responsibility the seller has is to list accurately the condition of the unit. Does it work correctly? What is the appearance? costs?
Whether a unit has been serviced or repaired? That has nothing to do with the sale. either it works within specifications or it doesn't.
One has to ask the question, why would you want to know whether a piece was "service"? and what does "serviced" mean anyway? checked for operational capability? repaired? I may be concerned about upgrades and would want to know, but even then, maybe not.
For example, I own a pair of Martin Logan Monolith III Speakers. years ago I sent the power supplies and passive crossovers in for repair. So what? I replaced the panels in 2006 with new ones and changed the woofers to the recommended Peerless woofers (much better bass response). Martin Logan did the repairs to the crossover and power supplies, so do you really care about that? I don't. If I were to sell the speakers, I would tell the potential buyer that I changed the woofers and still have the original ones if he/she wants them also.
But, what difference does it make that I had Martin Logan repair the crossovers and power supplies. The fact is that the speakers work perfectly now. I'm now using a Krell KBX electronic balanced crossover. I also had issues with my system and thought the electrostatic panels may be at fault so I ordered new panels. They are still in my office at home in the boxes because I found the real problem wasn't the speakers but a single tube in my preamp. A single tube!
So, in my opinion, no. it is not the sellers responsibility to inform the potential buyer of repairs or "service" what ever that means. It is, in my opinion the right thing to do to inform of upgrades done. Which I do.
If a potential buyer asks, I will tell them about repairs or service done.
All I care really when I purchase something on audiogon, is 1) does it work correctly? 2) what is it's appearance? 3) any upgrades done to it? 4) price
I'm finding that there are lots of lookie loos out there that want to treat a private sale like a retail store. They want to look and listen before buying. That is fine for new equipment, but really not cool for used equipment. One should know what they want before purchasing.
I will accept an offer of purchase, then allow the buyer to come to my home to personally pick up the unit and pay. Every time I've done that, I have the unit operating in my system so that the buyer can see/hear for themselves that the unit works and sounds correctly. Also, that takes away any excuse later for them to say it didn't work.
Well, yes it did. You heard it for an hours and paid.
That is really why I don't like paypal. It protects the buyer, not the seller. I can ship a perfectly operating unit to someone, paypal keeps the money in escrow until the buyer says it is okay. however, if the buyer was a lookie loo, they can say the unit didn't work correctly and paypal refunds the money. the seller then gets the unit back and finds the unit works perfectly.
That sucks.
One reason why I like to converse with buyers/sellers before completing transactions.
enjoy