how can you tell if a 1.8T has sludge buildup?

[JordanVw at aol.com]

while we are on the subject..  how can you tell if a 1.8T has a buildup of 
sludge? or if the turbo is about to go?? changing the oil, once a motor has a 
buildup of sludge, isnt going to remove the sludge..  or should it be SOP for a 
used B5 purchase to flush the engine, and drop the oil pan? (as well as do the 
TB job..$$$)   man, all this stuff adds up :<)

chris