Some things I've had to deal with both as a college student and a General Contractor, which may help:
Bombard the city/county with correspondense; phone calls, certified letters, email, meetings. Some of the most arrogant, cocky, stubborn, and frustrating people on the face of this planet work for your city/county, however they DO listen to the "citizens". Departments like the public works (trash, ect.), health department, and even our uniformed dohnut guzzlers are obligated to help, but you must use bill collector type tactics to get them to act. They have an obligation to correct problems like this with fines, tickets, ect. AND In most cases, the landlord has no other option other than to resolve these issues and evict them.
I've been on both sides of this war. But coming from the "good" side, you must have some sort of documentation to present to the appropriate higher power. I guarantee at some point your complaints will be legitimately heard and dealt with appropriately.
I hope this was helpful...