pascal30
before cutting the melon try pressing the area where the stalk was.. it should be soft.. then smell to see if it smells sweet.. I hope this helps.. I wish someone could give advise on mangoes though..
Personally I don't press fruit, if it isn't ripe it might bruise and go bad at a later stage. I'm lucky to have a good sense of smell and usually just sniff them, though this doesn't work with all types such as water melons.
I've just about given up on mangoes, you don't get much of a smell at all and even those that do smell good are often stringy inside. We usually buy them prepared in chunks or slices, though even then you can't always tell, other than that ripe mangoes tend to be a deeper colour. By the time you've peeled and stoned a mango you probably don't pay that much less per 100g compared to the packs.