Every animal loves plastic, you know

We used to collect empty bottles and cans at Tartarus to return them for the deposit (Yes, Tartarus is in one of those states). With the collected money we might buy a bag of candy or box of donuts for the staff on a special occasion. That all ended when the Hutt declared that the empty bottles (mostly empty water bottles) were attracting mice. That's right, apparently a mouse's favorite food is a plastic water bottle. 

While this was stupid and annoying, we'd mostly moved on and forgotten about it. Then Opie suggested this week that we collect bottles and cans to promote a fundraiser. Why is it cans for staff attract vermin but cans for a "good cause" are a delight?