It may be a bit lengthy, but I download HDTune (
www.hdtune.com ), do a SMART check (or use CrystalDiskInfo for that), then do a surface scan, check SMART again, then do a full-format using Disk Management, check SMART, then do a surface scan (again), and check SMART again, for any re-allocated / pending sectors.
If it passes the read/write/read test, then I deem it "worth" of being used.