How bad is a SMART Seek Error Rate

It does appear that different manufacturers use SMART values for sometimes radically different things, as you can see here:

My hard disk(s) in ReadyNAS is reporting high SMART Raw Read Error Rate, Seek Error Rate, and Hardware ECC Recovered. What should I do?

Seagate uses these SMART fields for internal counts, so this is a known issue with Seagate disks. Look for abnormal counts in other fields, especially Reallocated Sector Ct and ATA Error Count.

So when it comes to your actual question ...

If I am lucky enough for a bad drive to show a hint of failure such as scan errors or reallocated sectors, I know to get the drive the heck out of there. If no such hint exists, I'll probably spend many hours troubleshooting slowness and data corruption until I finally find that the hard drive is bad.

I'd say a good rule of thumb is, you can only expect SMART settings to be comparable within the same drive manufacturer, and maybe even the same drive model!

So when you're looking at diagnosing those SMART counts, keep that in mind... one manufacturer's "read error retry count" may mean something totally different than another manufacturer's. Sad but true. :(

Found this, not sure if it helps or not, Any SMART error is Not a good sign, back up your data now!

http://en.wikipedia.org/wiki/S.M.A.R.T.

B8 - End-to-End error Quote: This attribute is a part of HP's SMART IV technology and it means that after transferring through the cache RAM data buffer the parity data between the host and the hard drive did not match.