Also what reinforces this idea that it's the bolts is that in every case, the sound goes away when the wheels are put back on the car.
At first the dealership blamed the debris in/around the brake/rotor assembly. They said they cleaned it and it went away when I picked up the car, then the clacking came shortly thereafter. (a few days)
Then they blamed it on the tires.. I eventually replaced them and they went away right afterwards but then the noise shortly thereafter. (2 week).
Then they blamed it on remnants of my tire repair kit (Dynaplugs) which they found that little metal arrows had fallen off the plug.. They remounted the tires and said the noise was gone when I picked up the car.. It came back a few days later.
Then in my own attempt to diagnose, I noticed the retaining screw on the rotor was loose. Using some thread lock i tightened it. It went away right away, but then came back a few days later. I took it off, the bolt was still tight, put the wheels back on, and it went away. Then came back a week or two later.
Then I replaced my wheels tires again. The sound went away.. Then came back 6 months later. Then I replaced my rims. Sound went away, and came back 6 months later. Then replaced my tires again.. Same story.
So the common denominator is that the clicking went away for no other reason than the fact that the wheels were removed and re-installed.
Anyway just for reference, I'll let you guys watch some videos I recorded over the years on this very problem...
March '13 (if you listen closely it's present in this unrelated video)