A suburb, west of Melbourne.
Many people who don't live there like to insult it by calling it scummy.
Sometimes they're not far off the mark, but there are a great number of people who live there that are perfectly nice, normal people - some might even be more respectible than the people who insult them.
A: "Know that chick I met last night, she's from Werribee. Must be a total skank."
B: "Dude, my grandma lives in Werribee. You calling her a skank too?"