Yeah, I don't see the problem with this if the ads are just part of the environment and make sense in the context of the game's maps. After all, any seasoned FPS player ignores 99% of the visuals once they have seen them a couple times. They just become landmarks for the most part or blend into the immersive atmosphere. I doubt I will really even notice the ads much, but they might make the maps seem visually richer in a general way.
He cut the possum's face off then cut around the eye socket. In the center of the belt buckle, where the possum's eye would be, he has placed a small piece of wood from his old '52 Ford's home made railroad tie bumper. Damn, he misses that truck.