The skeletons provide an ominous warning to would-be timeshare scammers.
Apparently timeshare fraud is big in Puerto Vallarta. The timeshare salesmen accost you in the airport, waiting to scam you. They offer you assistance, throughout the city, sometimes even posing as shop owners or grocery store employees, and then they "kidnap" you and force you to listen to hours and hours of high-pressure sales pitches.
I walked along the malecón every morning, early, before the tourist crowds. The timeshare jerks shout at you from their booths, trying to get your attention. Every morning there was one guy who was pretty insistent. I ignored him every single day. On the last day, he finally said, "Hey, what's wrong with you! I don't bite, unless you want me to! Haha!" He kept shouting these things, and I said nothing. Then had the audacity to shout at me for being rude. Good grief!