D is a big one, especially if you fix/tune other people’s stuff. If it doesn’t have mix in it I always ask how they make their mix to make sure that when I tune it, it’ll be at least close to their specs. As for
@MontanaResident , Bob has a decent J-red collection as I recall.
For the OP, when it comes to selling saws I’ll either sell them as a project and list everything I know is wrong with them, or they are sold as good runners that I feel confident I could fuel up and run all day without any issues. I’m not big on “prettying up” my saws for pics, I’ll typically just hit them with some compressed air before taking the pics. I‘ve only sold a couple of saws with b/c’s included, but I typically try to make sure the chain is sharp and the bar is in good functioning shape (tip spins freely, etc)