Maybe I am just talking out my ass, but thisi s how it all makes sense for me.
Most of your engine bay cooling come from the side vents, and from under the car, and comes out up top. Now if you have air being pushed into the engine bay on top, the 2 jets of air are going to hit into eachother, causing eddies of sort (water does this, as I think air as well) and so the air ends up staying in there longer, and not just going in, over the components, then out. I know this is how it works in computer cases, and I've had crazy ammounts of work in that dept
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By this theory, the engine-lid fans would work GREAT, and actually help a lot, but the scoops would actually hinder cooling performance. Now if you were to take the driver's side scoop, and somehow rig it to be part of the air box, or onto a cone filter, then the air would be a true ram-air design and not get all into the engine bay and cause problems. The passenger's side scoop however would serve no purpose but to hinder cooling performance and for looks. If you were to close the scoop off so it didn't let air in, then you'd get rid of the negative.
Just a thought...please correct me if you have any reason why this would not be true.