Actually, it was a mess long before Instagram. Locals have been complaining about the trash and crowds for years. The pictures just finally caught up to the reality.
Ugh, that sounds AWFUL. What kind of trash was it mostly? Like, were there beer cans and food wrappers, or bigger stuff like broken bottles and camping gear? I've seen places where people just LEAVE everything behind and it's so frustrating. Did you notice if anyone was trying to clean it up, or was it just left there?