There WILL be lawsuits; this won't last long. Mark my word. The fact that you can't decipher whether someone JUST smoked, or smoked days, even WEEKS ago, is the issue.
Now if you have been blazing up in your car and they can blatantly smell it or see the smoke, that gives them probable cause and in-their-face evidence to support their draconian swab tests. Other than that, when the wrong people are targeted/profiled/ticketed, things will get ugly. Californian is becoming a fascist state more and more everyday.
People may eventually realize that asking for full re-legalization will cause more problems than it solves.