oops..wrong button...
anyway...i doubt that bert and doc do thier own sound at a show or in a studio. they probably show up, plug in, and do what they do best.
i'd be surprised to find out that the bad sounds you heard were the result of putting a pickup in an acoustic. i've heard an awful lot of acoustics with pickups, and as long as you spend a little money and learn how to use them, they can sound amazing.