2015 Ford Fusion Bad Smell?

I have a 2015 Ford Fusion. I got it almost brand new. It was used as a fleet vehicle. Anyway, I didn't realize whoever used it for the first 20 some thousand miles smoked in it until after I used it for a couple days. I could see smoke residue on the roof interior of the car. So I scrubbed that out. That took most of the smell out. But every now and then I smell a weird smell coming out of the vents. The air filter is clean. Would the cabin filter have any affect on the smell from the vents? Or is the smell coming from somewhere else? I will scrub the roof interior again, but any suggestions to get the whole system smelling fresh and new again would be helpful. Thanks!

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