Depends on the property. If they do agree to waive it, get it in writing AND bring what you got in writing when you check-in and have the desk agent confirm that it will be waived. Also, either don't let them take your copy or have two copies, so you have proof, again, at check out.
Mirage told me there was no fee on the upfront comped part of my stay and they would waive the last two nights resort fee if they comped the room which they did.