I recently ran on a USB drive the f3write, f3read, and f3probe tests. The size of the drive is legitimate, but there are some corrupted sectors indicated in f3read:
Data OK: 7.49 GB (15697680 sectors)
Data LOST: 124.00 KB (248 sectors)
Corrupted: 124.00 KB (248 sectors)
Slightly changed: 0.00 Byte (0 sectors)
Overwritten: 0.00 Byte (0 sectors)
The f3probe run shows the proper size of the drive:
Device geometry:
*Usable* size: 7.50 GB (15728640 blocks)
Announced size: 7.50 GB (15728640 blocks)
Module: 8.00 GB (2^33 Bytes)
Approximate cache size: 0.00 Byte (0 blocks), need-reset=no
Physical block size: 512.00 Byte (2^9 Bytes)
Am I correct in thinking that any bad sectors mean return this drive to the seller? Or do all USBs have a certain number of bad sectors?
No, it's not normal, it shouldn't have any bad sectors.
If the drive is new then returning it to the seller makes sense.
If the drive has been around awhile then repairing it is worth a try using
fsck.