Even if the cop somehow knew that for every 9 people that visited the store from Illinois to make legitimate purchases, there would be one who was buying illegitimate cigarettes, that would not justify harassing nine law-abiding citizens for each bootlegger that was caught. A cop who used such a strategy, however, could appear to his superiors as taking effective action against smugglers. After all, they're not the innocent people getting harassed by the cop.
The Constitution doesn't give a numeric probability requirement when defining probable cause, in some measure because there will be many inter-related probabilities involved. For example, if there is clear video of a person who is dressed very unusually (possibly uniquely) committing a crime, and a person dressed in such fashion is arrested near the crime scene, the person's dress may constitute probable cause for searching the person's car, because while it would be perfectly legal for a law-abiding person to dress in such fashion, it would seem highly unlikely that anyone not affiliated with the criminal would do so. By contrast, in the bootlegger scenario, the fact that it was not only legal for Illinoisans to go to the store and make legal purchases, but that many law-abiding Illinoisans routinely did so, would suggest that doing something that many other law-abiding citizens routinely do should not in and of itself be considered probable cause.
Are you insinuating this is occurring ? Or are you attempting to make another LIEberTARDian hypothetical?
Did you do the internet search for " cop sentenced"?