Jeff,
$ometime$ all you had to do to pa$$ a $mog te$t wa$ ?ooperate with the right technician to get an "EXEMPT" sticker.
Just saying my big block Chevelle with it's COWL INDUCTION hood got an "EXEMPT" sticker and that changed the playing field.
Depended on what year we're discussing and the your local governing Air Resources Board ( in some years and cases) and there are a ton of those
Remember a period where a friend had a new Mustang Cobra that had never been driven but was purchased by my friend as the second owner and CA would not let him register it.
In another car (66 K code) there was a period where since the car did not have a thermactor system the state required us to drill a hole in the original intake manifold and install a device in order to register it.
Yes often it helped if you got an operator or a referee just like today. Today take a little more work. Other challenge I've had over the years is that I've always "looked" like I could be a government worker - ie undercover plant from BAR to catch the shops breaking the law and handing our fines. To the point (example) I had a late 80's T-Bord for the wife that I had to smog and the station freaked out that the gas cap had a Mustang emblem on it (behind the gas door) I got by after I explained I was not an inspector and not from BAR by showing my work card and ID from the FD