In the video Jon Bois did about the 250something point college basketball game, near the beginning he describes some footage of a very fast, offense heavy form of basketball as "radioactive". I've always stuck with that description, something about the concept of a video being corrosive is a fun concept (as long as you don't think about it too hard).
Videos like this are highly corrosive.
Because it's a good video, the drive sounds absolutely lovely. But it's also got a LOT of issues. Like, the drive itself. Tons of bad sectors, errors, etc etc. But the drive still works, despite the issues. They can be mitigated to an extent and the drive can still serve some amount of data back the same way it was stored.
This is super toxic because I'm now of the mindset that, if a drive will still return most data without a significant time delay, it should still be used. When you apply this concept to drives in an array you start picking up some very bad behavior, of running drives that really have no right to still be there because, if they're not bad enough for ZFS to put them in time out.... why change it?