Oh, blow. I said I had never noticed that wording on any of the signs when I was down there. I'm still not going to deny any member of my family a sip of lemonade from MY cup if they ask.
Still, they obviously aren't serious about enforcing it. It would be as simple as requiring you to show your room key before walking out with your mug. Or as complicated as this:
http://www.disneyfoodblog.com/2010/05/22/patent-no-refillable-mugs/
I still don't like the idea of having to buy all of those mugs. So wasteful and toxic to the planet. I already have a whole cabinet of mugs that I need to thin. I came back from our Virginia vacation with two more that I will more than likely send to Good Will. (Remember, I'm a horrible person.) How many others go right into the trash? Presuming I go by an earlier poster's recommendation and purchase one mug for each of us for each trip, that's at least 5 mugs per year. We've been to Disney at least once a year since 2005, sometimes twice, although we've added children during that time. We'd already be at almost 30 mugs when we really only need one. (I'll *asterisk* this and say that we bought our first refillable mug on our last trip, so we have NOT been using the same mug year after year, as healthy for the planet as that may be.) My parents go 3 or 4 times per year. Does a retired couple really need to accumulate 8 mugs per year?
p.s. What if you're not a resort guest? What if you're a local who does a lot of business through the resorts, like the guy who drives the purple van? You'd never have a room key and you'd never have an end date to your current stay.
p.s. #2 I'm going to go back to my earlier controversy about not taking seats from children at Belle's Storytime. I noticed that MANY attractions at Busch Gardens had signs that stated that an adult must be accompanied by a guest under 54" to enjoy the attraction. Perfect! And I didn't see a single grown-up moaning about how they paid their ticket price and should be able to enjoy the little hot air balloons or dragon boats, etc., the same as any child...