I think the basis of consent ought to involve limitations of scope, such that discovery of a minor crime during the fruitless investigation of a major one should be treated differently. We want people to be cooperative with the police so as to minimize the incidence of violent crimes like the one the state troopers originally arrived to investigate. It's understandable that a neighbor got worried and called 911 (although we'll never know if the neighbor was genuinely worried or just irritated by the sexy sex noise). It's absolutely understandable that police would want to verify that no violence was going on after receiving such a report, even with the reasonable alternative explanation of sexual activity.

It's much harder to argue that McGacken's 10 year prison sentence has made society any better off. The cost of trying and imprisoning him may well exceed the social cost of his production (and presumable sale) of marijuana, but they have definitely reduced the incentive of people to cooperate with police investigating other crimes. To me this is a prime example of how 'the life of the law has not been logic, [but] experience' - the law has been consistently applied, but the result seems extremely unfair and may even have had negative economic utility.