Indeed, this is how it's supposed to work in an ideal world anyway. You only need to have some knowledge of the items and their tech to evaluate if they are useful second-hand or not for you. What parts wear and break and what are you able and willing to repair?

I have bought pretty much all my tools used. I usually buy low-tech solutions so my biggest concern most of the time is that the carbon brushes need to be replaced (and some models make this simple operation practically impossible, while in some models it takes under a minute). And I always look for dirty things that need a lot of cleaning since they usually go for cheap, and I'm cheap.