Use dumpe2fs -b filesystemname

Here are two examples (which are not very interesting as these filesystems don't have any bad blocks):

alice# dumpe2fs -b /dev/sde1
dumpe2fs 1.41.9 (22-Aug-2009)
alice# dumpe2fs -b /dev/mapper/VolGroup00-LogVol03
dumpe2fs 1.41.9 (22-Aug-2009)