the first one that entitles the bearer to a discount say 20-35% or $ 100 off to the listed price at the time of stay. When the hotelier raise its rates, the revpar post discount will also rise. classic stuff.
the second type is pre-selling capacity on eBay at deeply discounted rate, usually off 60-70%, targeting the leisure market. You buy the right to x number of hotel nights to be used anytime within a year.
Marriott is currently selling many week-end breaks and long week-end break (3-4 nights) in Europe (Berlin, Paris, Zurich,...)and week-long hotel stay in holiday destination cities that way. That temporarily improves their cash-flow but I don't think it shows as a RevPar until the room is actually used and expensed. The capcity sold at the trough this way is shield from any subsequent general rise in rates, flattening the prospect for improving RevPar.
This may not be material enough volume wise to impact negatively RevPar and positively cash flow to revenue ratio but is nevertheless symptomatic of how desperate some hoteliers are to sell unused capacity.
"Ain't quite so easy being a short these days is it?". Certainly it isn't but it shouldn't be anyway, it just requires as much if not more discipline than being long. And it's certainly worth it.