After reading this and thinking about what might be done I have one suggestion, it appears to me that your friend is probably renting an apartment or house as they do not care about the Pug doing his "business" all over. So how about sending an anomonous(sp) letter to their landlord about how dirty the place is..the landlord comes in sees the damage and evicts them or the dog. If it is the dog then he at least will have a chance at life in a home that he is wanted.
I really feel for this poor dog, little to no attention, no training. Good luck with this and please keep us posted.
We really need to change the laws in this country on what is abuse...
It Is What It Is