No disrespect intended or implied, but I,be treated my Stihl saws like crap for the last 20 years and they all still run great. I keep bar oil in them and always use Stihl 2 cycle oil to mix my fuel. I only clean the bar if I take the chain off for some reason which is rare. I file the chains about every other tank of fuel. I only cut about 6 cord a year, mostly hickory. The air filter area should be blown out after every use, but mine only gets cleaned a few times per year. Point is that saws are pretty durable so long as you don't ever use straight gas in them. Straight gasing is the most common cause of death for any good saw.
I'm gonna tell on myself here as it was recent and I've probably used saws for at least 30 of my 46 years of life.
The week before Thanksgiving I was using my 290 and put gas in it that I thought I had pre-mixed for my 020AV (40:1 saw) well I fire it off and go to dropping a 24" across tree the saw stopped and wouldn't refire. The power had never dropped it just stopped. I fired up the 020AV and ran it until it ran out of fuel trying to get this half cut through tree on the ground. Filled the 020 up with the same fuel I put in the 290. Before I went back with the 020 I attempted the 290 again and it fired right off. So I put it back to work and dropped the tree, but not before it stopped running again. Suspicious of what was going on I pulled the plug and looked in the cylinder, nothing seemed or looked amiss. I suddenly had a oh no moment and dipped a white paper towel in the gas. The paper towel didn't show an oil line on it and my stomach sank. I looked up some cylinder kits and started shopping for a new saw thinking I had ruined my 290. I went and bought the new bigger saw and had resigned myself to just rebuilding the saw. The stihl dealer suggested just refueling it and running it. His position was "you can't hurt it anymore" I have since fueled it and it runs just fine. Moral of the story is just cause you screw up with fuel/oil doesn't mean your saw is junk.