I'd like to know too.
I cancelled a few years ago with no problems but that was before ppl started posting about it not always saying "no cancellation fee".
I have never had a problem cancelling a room that was booked with "FREE CANCELLATION". I have always received 100% of my money back. I have done this as recently as two months ago.
I was one of those that unfortunately reserved a room with a $25 cancellation fee. And wouldn't you know, I had to cancel that reservation. Ugh. They would not waive it. Claimed it was a resort charge not their fee. If only I'd gone with the first room I was going to reserve...it had free cancellation and I just assumed the sister resort did too.
I canceled 3/24/2016, and although the confirmation page (when I paid) said there's a cancel fee, I was not charged it. IIRC, the day I booked (3/14/16) was at the start of them mentioning the cancel fee, so perhaps I was 'grandfathered' in, with no cancel fee. So, I'm no help really!
Sometimes you can still get it, sometimes not, you have to open up the fine print on the final page to see. It says some resorts require it then will say if yours does. I know it showed up for CS, I haven't checked the Disney page to see if it's required there.