how effective are noise makers such as rattles or propellers when added to a lure?

Noise makers and rattles can be very effective on ACTIVE lure presentaions. By that I mean that lures that you cast out and retrieve back to you immediately or in some sort of cadence. The reason being that fish have that "letteral line" that pics up vibrations and sound waves in the water. When you walk a Spook or shedog across the surface the ball nocks back and forth inside the lure to make a sharp "pop" that fish are attracted to. Same goes for those little "mini" inserts" that you can put in plastic lures. the big blades on spinner baits also make quite a vibration in the water that fish can hear and feel. The point is that for them to work, the lure has to be moving.

I DO see alot of "noise makers" and bells and whistles that are attached to popping cork type set ups. I believe that all these bells and whistles are more for the fisherman than the fish...The popping cork by itself makes enough splash and noise, immulating fish hitting the surface of the water. As usually the case, there is rarely a 100% definitive answer for all situations.