We attended a timeshare presentation in exchange for promised gambling and buffet voucher. We signed a paper saying "2-3 hour presentation". So it seemed like a straightforward deal: they get our time (3h30 counting transport) and we get the freebies.
Our guide (William) was very aggressive. We told him about the conditions we signed for (be done in less than 3 hours). He said that the tour had to take more time and that he had never met such unpleasant customers. We went through the tour and he was more interested in talking to us about his life than about the timeshare. So we got the story of his life instead: he lived in San Francisco, found his wife on Facebook, was currently getting a Masters in Las Vegas University...
The buffet vouchers were useful.
However, the gambling vouchers were total scams: they can only be used on a few machines and winnings are not cashed out. Basically you get to play until you lose everything.