Ok, since you're rilly new here I'm gonna assume that you might be new to buying used chainsaws and give you a couple tips that we might be skipping over. I would tend to believe that all Stihl dealers are stand-up individuals, but that might not always be the case.
To tell how much a saw has been used, you look the entire thing over for paint wear.
If the bar is burnt or wear out, it's been used a little. If the wear pattern is fairly even then it's just been used. Bad spots or burn marks are not so good. A "brand new bar and chain!!!!!" is not really a selling point. As an avid chainsaw buyer, I have oodles of bars and chains laying around and even if I wanted to buy a brand new one I'd like to shop around and pick the exact one I want.
If the paint on the bottom is wore out, that means that it's been bounced around in the back of a truck. That's not always so bad, because I could drive around with a saw in my pickup for a year and only use it once. The ones you are looking out for are the ones that also have bad cracking somewhere or a chunk missing or have been bounced around in the back of a tree service truck for a year and used by half-drunk laborers who don't have a clue.
If the paint on the starter cover is wore out, that's a bad sign. If the cover grid is full of muck, that ain't good either. If it's got a little sawdust, that's normal. If it's immaculate, you need to figure out why. Is it a brand new cover, a brand new saw, or did an unscrupulous logging company blow it out with an air hose and some Windex before they dumped it? You should be able to read the model number on the starter cover on a 361. I think the felling sights come painted black on that side and they should probably have some paint left too.
If the paint on the front of the powerhead is wore out, that's no good. I means someone has bashed it off a bunch of logs. If it is worn, check and make sure the dog mounting points and the muffler and the oil tank and its filler neck are all still intact. One of the 361s I bought this year had a busted dog mount that I haven't yet fixed to my satisfaction.
If the paint is wore out on the clutch cover, that means the thing has cut a fair number of stumps or bashed against something in the back of a truck. A 361 really shouldn't be a stumper, so watch yourself.
By now, you should have noticed whether any of the handles are cracked or any of the controls broke or missing. If anything has been intentionally removed or modified, someone has either used this saw in a professional manner or done a half-assed fix on it. If they were making money with the thing, why sell it? If it was busted, was it busted so badly that it wasn't worth fixing right?
I think I covered most of it. If not, just get a compression check and flee the crime scene before forensics shows up.