I created a similar app a while back called Clnli. The idea was to create a network of bathrooms by partnering with restaurants, small shops, etc. that already do a good job of keeping their bathrooms clean (Starbucks, froyo places, hat stores, etc).

Users would pay a weekly/monthly/yearly fee (non-renewing, good for travel) to get access to the network and they would be able to unlock bathrooms directly from their phones. No need to ask for a key.

Stores would get paid on a monthly basis for keeping their bathrooms clean.

The primary problem was convincing stores to join the network. I talked to a very very large number of store owners and managers in and around downtown San Diego. The value proposition to the store owners just didn't seem high enough. The idea of charging people to use bathrooms didn't sit well with some owners, and others flat out refused to open their bathrooms.

My starting market was parents with young kids. That market seemed quite receptive to the idea.

I hope Looie is able to pull it off. I still think its a great idea.

EDIT: Having to use a separate access key seems meh, when we all have cell phones. Clnli integrated with lock systems like http://resortlock.com/ and displayed a code in app. Using BLE/NFC would have been even cooler.