Eating fruit at various stages of rot is a personal preference. If you like your 'lopes soft, then you want the less firm/solid sounding ones.
For example, tap your desk. Hear that firm clear sound? Now tap your seat cushion. See how that softness cuts down on the thud?
Tapping melons can yield somewhat similar results. Generally, if you want the meat soft, choose the softest mellon and the stem area should be getting soft, too.
Sure, if the 'lope is too soft…it’s too rotted. So, you’ll have to go the trial by error route.
(there’s porno in that post somewhere.)