I found this
ebay listing rather entertaining. A lot of nice covers that were ill prepared, poorly thought out, or just plain mistakes that were made in the cachet and/or cancellation process. Someone spent a lot of time "typing" commentary for many of them, too.
Quite a photo essay here, and with only two bids, it is a relative bargain if anyone is inclined to be interested in such things:
http://www.ebay.com/itm/US-Cachets-...35686wt_1025