Here in Kalifornia, I'm one of the guys certified to do the sniffing.

It's a little different here than other places, from what I understand.

My sister lives in WA and has to smog her car (my old 91 Caprice cop car). Their test techs know how to operate the machine and that's about it.

I have to know how the whoel car works, be certified by ASE in electrical, engine performance and advanced engine performance, take a series of rather expensive classes from teh state and demonstrate proficiency in the subjects taught. Then I have to take a lengthy test and take an update class once every two years. It's really not worth it in a lot of ways. I also have the distinct pleasure of dealing with the State of Kalifornia looking over my shoulder while I perform these smog checks, and they tell me they can take me to jail if they catch me making a single mistake.

Now we test anything newer than 1974 (or 1975, I can't remember which). Cars newer than 4 years don't have to be tested unless they come in from out of state.

Cars newer than 1995 (OBDII) have to also be checked for readiness flags. That means that you can't clear your codes to get rid of the check engine light and then run out and test it before it resets. We have to let the machine check to make sure all but 2 of the test groups have been run or the test fails and you have to bring it back with the self diagnostic tests run before it'll pass.

Big PITA.

Clay