Bill,
What you say regarding the "expert" beekeepers is very true - it is
vital that all reasonable doubt of damage is being caused by other
factors is either removed or taken in to account.
Here in France many hives that have "suffered" from "Gaucho" would have
died anyway due to poor treatment against V.j. and it is too easy to
blame an outside factor beyond the beekeepers control.

But at the same time a pesticide hit does not help the overall health of
a colony - esp. if the toxin delivers a sub-lethal effect.
E.F.B. is well known to raise its ugly head when colonies have or are
under stress and then conversely it is the Agro-chemical firms who fall
into the trap. They then have the tendency to blame the disease for the
problems and not the toxin. So as you say - "experts" won't wish for
outsiders to look in to the products. It can't be them so it has to be
the "beekeeper"!
Neither side can have it both ways as I am hoping that you agree.
Peter