[s-cars] Loose Spark Plugs, the cause?

[S4quat at aol.com]

  It seems that it happens to just about everyone.  I've never heard of it
occurring in another engine.  It seems so strange that the magical ($20.00
retail) spark plugs on these cars come loose.  What is the cause?  I've heard
the theory that it was due to the cooling cycles of the head.  That seems
reasonable.  Why didn't Audi ever officially address the problem?  It seems
odd that Bosch never did anything.  Do stock and modified engines have the
same problems with the plugs coming loose?  Anyone ever consider detonation
as the cause?  I have an RS2 setup on my 92 S4 and have had the plugs come
loose many times, although I've never had them come all the way out like some
listers(thank God).  I've have heard a little detonation on my car in traffic
on a hot summer day(even at altitude, 6,200 ft.), but only a couple times.
It has never been a big concern because I think I'm running plenty of fuel
and I'm at altitude and its rare that I've actually heard it detonate.  But
the fact is how can you actually hear detonation at WOT 5,000 + RPM.  Perhaps
our cars even stock, detonate more than we think, yes the ECU may then back
off the timing.  Perhaps it is this chronic detonation that Rattles the plugs
loose.  I'm not sure if this same hypothesis has been posted before, but it
seems so strange that a solution has never been found for this problem.  Does
anyone have any other theories?

Michael
92 S4
Jackson, WY