You really need a Cambodian Guide
I just got back from one month of a Cambodian adventure. From my experiences, you really need travel with a Cambodian friend. I got into many of the places that usually are only there for Cambodians.
You got to love restaurants that as you enter there are a bevy of beautiful ladies waiting for you to take them to your table and then negotiate for more. The Karaoke places can also be fun if the moment is right.
So, if you find your self in Cambodia, find yourself someone to show you around. It will be well worth it.