I have come to the conclusion that in most waters, fish are not bothered by boat traffic and outboard noise, having caught way too many fish (walleye, Northern, crappie, smallmouth, etc.) that were definitely not bothered by outboards, boat traffic, my boat being only feet away when they struck, etc. When you think about it, fish in most lakes and rivers grow up hearing boat traffic more or less constantly, so it is probably just “part of the scenery” that they don’t really notice. I also doubt that fish have the ability to associate motor and boat noise with human predators. In clear water, very shallow water, and possibly remote lakes or rivers that see very little boat traffic boats and motors will spook fish, but the water around a Mississippi wing dam is not clear, very shallow, or lightly travelled.
As a rule of thumb, the best walleye water around a wing dam is the water just in front (upstream) of the dam at its base. (Like all rules of thumb, this is not always true.) So, when I troll a wing dam, I try to keep the boat just above and parallel to it so my crankbait or three-way rig is running in that area. This requires some care, as the current will push your boat over the top of the dam if you are not careful, which can lead to snagged rigs, or possibly a dinged lower unit if the top of the dam is close to the surface. I make several passes back and forth between shore and the tip of the dam, keeping my boat just upstream from it, and see if anything hits.
Another rule of thumb is that at normal to low water levels the end of the dam closest to the channel holds the most fish, along with the plunge pool behind the tip (make a couple passes up and down through that, too), but I know of several wing dams where this is not true.