The last time we attended a "time share presentation" for a "free cruise aboard Royal Caribbean", it turned out that the taxes, port charges, and SERVICE CHARGE were nearly as much as I could have booked an RCI cruise for. Not only that, they wouldn't allow me to select the date. I could select three BLOCKS of dates, and when, and if there was an "empty cabin" then I'd get to go. I told them where to put their "Free Cruise".
The closest to an actual "Free Cruise" we've taken, was $79, plus port charges, and taxes for a seven day. That was on "Premier Cruise Lines, SeaBreeze" just before the line folded.