In the early 2000s, Josef Woodman's elderly father, David Woodman, unveiled vacation plans that deeply alarmed his son. He was heading down to Puerto Vallarta, he announced, to find a Mexican dentist willing to cut him a good deal on a mouthful of new teeth. Would Josef like to come along, he asked, for “some sun and sand”?
Josef recognized instantly that his chances of heading off what seemed to be a potentially calamitous scheme were slim. His father, a 72-year-old retired businessman, had always been a “little bit of a geek and very eccentric,” Josef recalls. Weeks earlier, he'd disappeared down an internet rabbit hole in search of deals after an American dentist had quoted him a price of $34,000; by the time Josef got involved, David had long…