Well, I live in the South, and my family doesn't rinse every can. Our cans are picked up once a week. And no, we don't have bugs. So cans not being rinsed aren't a problem. And honestly if they are, Disney will have to take care of that problem. I'm pretty sure if you are given a room covered in bugs, you would request a different room.
And people that don't sweep up crumbs from breakfast, even with kids, aren't going to be helped with daily housekeeping. Because those people are the same ones that don't sweep up after themselves at all. And those people are going to cause a mess where ever they go. They are also the ones that can be charged for extra cleaning when they check out.
I just don't see it as a big deal that some guests are turning down the option of housekeeping. Heck, some already do it. They simply leave the Do Not Disturb tag out.
If it doesn't work out, because people are pigs or because the rooms get trashed or whatever, Disney will stop offering the gift card. And if they don't stop offering it, the rooms will end up trashed and no one will want to stay in them. And Disney resorts will end up empty or full of messy people. Okay. No one is forcing anyone to stay at a Disney resort. If they are nasty, they are nasty. There are certainly hotel chains that I refuse to stay at.
