Personally, I wear blue jeans/contractor pants and button up shirts and my hat really everyday. I can pass for "high class" if I need to, and can pop the collar, turn the hat at an akward angle, slouch and pass by as a bum.
If you mean a camo pattern, there really isnt one. Personally if SHTF, I would only move around in urban areas at night, and even then its woodland camo pants and my black combat shirt. Now given I also have a Gen II NVG monocular to make night travel slightly easier, but still hide and look normal.
In short, blend with the surroundings as best as you can, or be indiscreet if your out of place (think the opening scene of the Delta guy in Black Hawk Down)