I played the role of 'Sniper' for several years; I'd have to say that camo makes a difference. Both from the number of times that people walked by me (within 30') and from the number of times I spotted someone in a blue jersey that was moving through a tree line (who I am sure I would have otherwise missed).
Additionally, camo/ghillies are not just for static players. My favorite play in woods games was to dash head to mid course and hide. My partner, the rabbit, would run up a little slower, pass me, and look for the enemy line. Once contact was made, he'd fall back past me to the rest of our team's line (but slow enough to draw the others along his path). Once the fire fight started I'd drop in on their rear and break their ranks.
I also spent a great deal of time about 15' to the side of an assault squad. Once they engaged the enemy, I'd push through to their rear. The ghillie worked wonderfully to avoid detection. It's easy to talk about the number of players that you spotted, but how many camoed players have seen you and decided not to engage?