I sharpened a few chains earlier this week that someone had sharpened on the back side of the cutters.
From the looks of it they had the chain on the saw backward, rain it like that for a while and "sharpened" it a few times like that. Was like that on 2 or 3 of the 10 chains brought in!
I'd poke fun at the saw owner....but I can't because I have done that same thing a few times in the past myself I usually catch it prior to starting the saw, but a couple times I actually tried to cut and realized instantly that something was wrong! One thing is for sure....each time I do it my face turns red...either with anger (when I am by myself) or with embarrassment (when I am not)!
I purchased a used / like new 266 that was sold from another local dealer, not mine he spun the connecting link, cutter on the chain backwards just one tooth. I sold it to my dealer, he fixed it and sold it.