I know of a few examples, which weren't horrible, just took a little time to
work out the kinks... The Burke Museum at the University of Washington has a
great cafe which is located above the archaeology department's storage area.
 Some of the cafe staff would sweep up at night and push the detritus down a
floor vent, which lead to the storage area.  Coffee beans and rat poop can be
confused without close examination.  Also the crumbs of food caused concern
about pests.  There hasn't been much trouble with this as far as I know since
the collections manager let them know about the problem.  Sometimes food
odors filter to the lower levels also which can lead to tummy rumbles.  The
main thing about the cafe at the Burke is that it has great espresso and a
fun staff, which is a big plus as far as I am concerned.

Paula Johnson, UW Museology Grad Student