We did that as well, to get three free nights in a resort. We signed up for the last possible slot in the day for the day we were set to check in to the hotel. We also borrowed a friend's baby (friend was traveling with us).

The salesman was tired and ready to go home. Instead of the regular 2-3 hours, we spent 15 minutes with him while the baby fussed a bit. Then he handed us our hotel voucher.

Just be strategic. Like most things.