good luck trying to fool a well trained dog. you cant hide the smell with another smell. the dog just smells whatever you are trying to use as a masking agent and your weed. an example is coffee if you use coffee the dog just smells coffee and weed.
My feelings are it might make the dog act like he had found something if he started acting frantic, thus giving them reason to get a warrant and search the vehicle. I wouldn't be spraying anything that would get the dog excited.......
just spread cannabis bits all over the house or car... the doggie will alert on EVERYPLACE you put it.. use stems, dust, leaves... anything