How do I prevent the homeless' from pooping on my business' back entrance?

Hi Bob... is the doorway recessed? If so, you could install a steel gate flush with the wall. Maybe some CCTV but I'm guessing that wont deter them too much. The only other option is to move premises or get involved with the council to see if there are any improvement programs for the area to help these guys and gals.

Shaun