Six years in Thailand taught me how to determine the ripeness of mango and pappaya. And also taught me not to but avacado in Thailand. Most came from Australia, and while they might be rock hard, once you cut them you'd find them rotting already inside.
One difference with mango in Thailand is that the Thais prefer to eat them unripe. Same with pappaya. Pappaya is most commonly used unripe in the ubiquitous som tam, although mango is also common. Both are also sold on the street in long strips to be dipped in a combination of sugar, salt and chili. While it might not sound great, it's actually quite delicious, though to be honest I preferred pineapple, which added a sour component to the sweet/salty/spicy dipping mixture.
RE: Is It Ripe? How To Know When To Eat Avocado, Mango, and Papaya, Contributed by @sharingeverybite