I doubt camo is useful and I personally go for bright, fun colors, but I thought this might be a useful exercise:
Look at your map stats for an idea of what maps there are and how often they show up in rotation:
http://mwomercs.com/.../stats?type=map
Tourmaline Desert and Canyon Network pop up the most frequently because they have no snow/night variations. The idea is that they show up as often as some version of any other map.
They may have put Terra Therma in the same category as Tourmaline/Canyon; it certainly seems that way.
Caustic Valley and Alpine Peaks have only one version each, but for whatever reason, they are in the same category as the rarer maps that have two variations.
Camo doesn't make the slightest difference if people have night or thermal vision on.
Common:
Tourmaline Desert
Canyon Network
Terra Therma
Uncommon:
Caustic Valley
Alpine Peaks
Forest Colony
Forest Colony Snow
River City
River City Night
Frozen City
Frozen City Night
Maps with substantial white:
Tourmaline Desert
Alpine Peaks
Forest Colony Snow
Frozen City
Maps with substantial dark brown:
Terra Therma
Forest Colony
Forest Colony Snow
River City
Maps with substantial mid-grays:
Forest Colony
River City
Canyon Network and Caustic Valley are all alone in their color schemes. You could say Tourmaline has a lot of dark brown, but usually the ground is your backdrop, not the rocks.