Yeah, by all means they can block further writes to the drive, but you should always be able to read from it, even if the drive can't guarantee that the data is

Yeah, by all means they can block further writes to the drive, but you should always be able to read from it, even if the drive can't guarantee that the data is correct. I've recovered many hard disks that have gone bad in various ways, including multiple Seagate Barracuda 7200.11 drives that suffered from the BSY bug, and I've never had a disk that I couldn't recover at least some of the data from, even if that meant hooking up serial cables and re-reading the data multiple times (eg: Spinrite). But a drive that disappears completely when things go bad is never a good outcome.