Turning down the search is easy, assuming you're sober and legal:
Q: Are you cool with me taking a look around youe vehicle, since you have nothing to hide?
A: "Actually, I gotta say not to the search, sir. I'm 100% sober, I am legally carrying and you saw my permit, I don't do drugs and don't have drugs, I'm a hard-working musician with a car full of amps, trying to dodge idiot drunk/stoned drivers and just get home to my bed. I want to sleep, not spend an hour cleaning out my car. You know scumbags, and you know working man, it's pretty obvious which I am. So no, I don't want to be searched, I don't consent, respectfully."
At that point, ticket or released, but if not, it's motherfccking ACLU, lawyer, supervisor, video everything time. I respect cops, I follow the law (I don't ever even speed). But the moment I get violated, the law is suddenly my best friend and that cop has a headache for 5 years with my name on it.