SSD failure modes

What is the expected behaviour of bcache when an SSD wears out? Do SSD's internally do a verify after write to ensure that the data has made it to the 'media' correctly and report a failure if that's the case? Does (or can) bcache do a verify itself?

And what about an SSD that fails hard (eg linux detects an unplug)? A system crash is acceptable in such a case if the cache was in write-back mode, but what are the chances of rebooting successfully with the outstanding cached writes now lost?

Thanks

James