Cannot delete Podcasts IOS 5.1

When I synched my iPod Touch 4th Gen, IOS 5.1 to iTunes 10.6.1 on my Mac I saw dozens of podcasts appearing in the iTunes "DEVICES" Podcasts list that were not visible on my iPod.

When I deleted them from the iTunes "DEVICES" Podcasts list, they appeared there the next time I synched the iPod.

I changed my iTunes preferences to "SYNC all Podcasts" and then for the first time all of the extra podcasts appeared on my iPod.. good, sort of..

I then deleted these extra podcasts one by one from the iPod, yet when I re synched the iPod to iTunes, they reappeared in the iTunes "DEVICES" Podcasts list.

These podcasts do not appear in the iTunes "LIBRARY" "Podcasts" list, only in the the iTunes "DEVICES" Podcasts list

Where do they reside and how can I delete them?