Our last landlord tried keeping all the deposit and charging is for more. When we moved in, I took a whole lotta pictures. I took pics when we moved out and did my research regarding local laws and looked at how frequently tenants win in small claims court here. Over 80% of cases are in favor of tenants.
So I wrote a very professional letter to the landlord and property management company. I provided this information and sent a CD with copies of before and after pics of the place with notes, like the place hadn't been cleaned before we moved in, there was a hole from the second bathroom to the outside, large enough to fit a fat raccoon, husky fur everywhere, nails, hooks, and tacks in the walls, footprints on the ceiling, human hair on the walls and ceilings of the main bathroom.
I informed them they had 60 days to return our deposit or we will take them to small claims court. Local laws state that if a tenant wins, we receive 3x the deposit, and the landlord pays all court costs and fees. 58 days after sending the letter, we received our deposit with an apology for "confusion."
These people are dependent on ignorance. Be aware, be knowledgeable, and make them afraid.