Putting a sticker on a car that should fail in MA could result in loss of inspector license and drivers license for the inspector as well as a hefty fine to the shop ( thinks its up to $2500 now i could be wrong on the fine though).
Why should anyone risk there lively hood and reputation to put a sticker on a illegal car? The reality is you have avenues to take with MA if you feel your being taken advantage of, Want to know what the tint laws are? Simple call the DMV or go the MA registry site where all the state inspection laws are posted. Go in with that knowledge and ask to to see the tint meter results. If you choose not to educate yourself and just bash the shops or people then you have no one to blame but yourself for the outcome. Anyone who has gotten a a failure has the right to challenge it by calling the local DMV and requesting a challenge. They will send you to a shop of there choosing and there the results can be challenged. So for that friends Camry with the phantom exhaust leak why not challenge it instead of bashing the shop if your so right? Its not like he can go to another shop with out some sort of repair made since its in the registry for a exhaust failure. That is the first thing there going look at.
Edit:: As was previously mentioned MA Registry does sit in parking lots and sends cars and people to bribe that wont pass to shops all the time.