So, I have been having this problem with critters in my shed. (Sounds like a euphemism, like "bun in the oven.) Even after taking measures to keep grass seed and the like sealed in plastic bins, the mice still find reason to go in there and poop everywhere.
I decided I had to take matters into my own hands and do away with them, one way or the other. As I am not man enough to face the consequence of my own actions, I decided against traps and went with the "green block o' delicious poison" method. It worked pretty well; after about a week, I stopped getting customers.
I'm assuming they just went off and died somewhere convenient. One time, though, my brother had a similar problem, albeit in his mouse-infested apartment in Brooklyn. He went the poison route, and one of the mice went off and died inside his oven, which ended up being a really really bad scene.
I was just thinking that if some anonymous stranger put out a box of a dozen poisoned donuts where I work, by the end of the day you would have 12 dead people. We will eat any strange donut we come across, no questions asked.