Of course, there is always a catch. This one is pretty simple, though. If you book through a third party, you can't get your resort fee waived, period. In other words, it only applies if you make your reservation directly with TI. And, yes, that might mean foregoing that lower room rate. You'll have to see which way pencils out to more savings before you click that submit button, but at least now you know that mandatory resort fee isn't as mandatory as once thought.
(PHOTO: Treasure Island on Foursquare)