cdxx, you do have a point about the various grades of liners, there are acoustical methods for determining where to install silencers/attenuators. I choose to specify attenuators where needed, and I do cleanrooms for pharmaceutical manufacturing facility HVAC, where ANY contaminant in the ductwork is a no-no.
In an office setting, it is my belief that lined duct should not be specified either, due to the fact that the duct may be used for 30 years, and over that period of time, indoor air quality may suffer from particulates being sheared off of the liner.
Also, when existing lined duct is tapped into, the cutting of the liner causes particulate to become loose in the ductwork.
Brush up on applying sound attenuators and other such devices and you will eventually become familiar with and anticipate noise and its causes/propogation.