M-Cameron...here's a test: Go to the hood and shoot off the loudest gun you have. Wait for police (pack a lunch).
Criminals who do not carry firearms on them except when committing crimes, then stash them, certainly do not carry suppressors as well. They don't need suppressors (big, bulky, expensive) because in the places where they shoot people (the ghetto) the sounds are common and unremarkable. In other places (the stop-n-rob) it's not a gunshot that brings the police, but the clerk (or witness) on the phone after the robbery.
So that leaves the myth of the Hollywood hitman. I guess if the NFA suppressor law gets repealed they could then use a very good fake ID to buy one at the gun store...maybe.