Some places if they search you car on base of "smell" it won't hold up in court. But some places like Maryland it will and they have the right to search your car. Just check the laws in your state.
Well I know where I live that smell is a probable cause and therefore you could get fucked over. But i'd try to deny it as much as I could to get them to not search my car.
"Are you fucking shitty me you fucking lowly street patrol rentacop? You dare compromise my undercover work because you think this vehicle smells like dope...give me your badge number, wait till my superiors hear about this shit!
Uh, Yeh it most definitly will. They'll make up bullshit, whatever they want dude. Red eyes, Acting suspicious, etc... They WILL find a way. Finally, someone who's posted something intelligent. If you smoke cigarettes, Tell him you just had one, and that would be the smell. If not, you could go along with? " I'm sorry sir? I don't smoke marijuana, and none has been smoked in this car. " If he's like a Jersey cop, it's all about the night the cop's had. If he's pissed, prepared to be fuck. Hard. By the law.
"Marijuana, Sir? No sir. I only smoke the finest of crack rocks..... I've got one waiting on me at home."
Yeah I'm smoking. Why the hell do you care? Give me my $100 ticket and let me go. But hey, at least I didn't run a stop sign or was speeding.