I thought of this thread when I was watching Colbert last night as well! It makes one think - perhaps the reason the prisoners in the houses of lamentation are not killed, per se, but rather 'left naked to the lidless eye' is so that, legally, Sauron and the credit card companies can still try to collect on the debt.
Incidentally, Colbert is a confirmed Tolkien fanatic - see the old interview
here, for instance, where he even laments the changes to Faramir's character in the film.