The only way to test this would be to have your anecdote together with the complete marketing profiles of your friend and his wife. If such a profile could even be compiled in principle, from it we would be able to tell whether your friend or his wife had generated any non-audio pool-related signals, or whether they had seen other pool-related ads recently. Also, it'd be nice to know how often people in their marketing categories receive ads for pool fencing. Could be an astonishing coincidence.
It’s definitely a difficult one to test in a scientific way. But they 100% had no interest in pool fencing, living long-term in a rental townhouse. They chose the phrase specifically to be something they had no interest or search history in.
