It's a weird ass shader thing. It even changes color based on what's next to it. For example if you have different bodies on the robot, the color changes. I just don't like it. It should just be clear periodThe squirting looks like a green-brown colour? I'm really not sure what it is but it's rather off putting. As for the general colour schematic yeah, It's odd - as well as the fact everything looks "shiny and reflective" - reminds me of the early Xbox 360 days when Unreal became a prominent figure in the scene - everything was dark and wet looking.
See Gears of War specifically, shiny, wet looking and a fuck ton of AA issues.