Don't worry about being shot down, I would imagine that the majority of self employed technicians operate in a similar fashion. My only advertising consisted of a leaflet drop when I first started on my own, about twenty years ago now. It did produce a few customers at the time some of which are still with me. Other than that it has always been by word of mouth so I guess I have avoided the majority of time wasters although a few have slipped through now and again.
Regarding the Rogue Trader type of program, it wouldn't be necessary if all traders were honest so it does fulfill a purpose for the public but wouldn't it be more balanced if they also showed an example of a decent garage who provided a service to a happy customer occasionally?
Just my thoughts, hope I haven't buried my head too far in the sand!
Regards Colin.