[Query] Creating Slums

My mapping and artistic skills are mediocre at best so I've been using a lot of the mapping tutorials people have been kind enough to make.  The only problem is that I haven't been able to find one on how to make decent looking slums with the standard tile set and since I ain't the most artistic person, I don't think I'd have much luck making my own grimy looking one.  If anyone can give me a few pointers or even point me in the direction of a threat that can, I'd appreciate it.

Hmm, well... slums would have a lot of trash and broken things laying about. And homeless people. The houses should be very small in size and tattered-looking.

Another trick you might want to use is a little screen tinting. If you make it a little darker it can seem a bit more depressing. You could also add a fog layer if the air is unhealthy there, too.