Cops have lots of practice with the rights words to say about the person's driving, behavior, appearance, and so on. Or the right things to see. Like a ziploc bag, even if there's sandwich crumbs in it. Or ashes, "residue" (i.e. brown spots on anything), etc. Or constricted pupils, even though it's sunny outside and therefore expected.
My favorite one I saw was Krispy Kreme leftovers being "meth". https://www.npr.org/sections/thetwo-way/2017/10/16/558147669...
https://www.nolo.com/legal-encyclopedia/can-police-use-dogs-...
He still should not have cooperated, of course. Any extra effort you force the cops to go through gives you some protection.
AFAIK this is only true in a very limited set of local jurisdictions.
The use of drug dogs to manufacture probable cause is pretty well documented.