The BB's I've used in the past, for the most part, have been processed correctly. The biggest problem I've had to deal with is the B1G1 Free night EEO is not processed correctly. Very few times have I used one where the bill at check-out correctly processed that coupon.

Personally, I wonder if part of the problem is Marriott's systems might be a bit complex, confusing, or just hard to use. If you add to that type of system an environment with a high-turnover rate, you are asking to cause your customers problems.