You're in the supermarket and some wizened old lady is inspecting some unrecognisable yams. After discarding two or three she selects one based on criteria outside your knowledge. I haven't the faintest idea how to tell a 'good' one. Mind you, I can pick out male Sicilian eggplants - less seeds.
But the one that burns me are the blue crabs. Hundreds of 'em, all looking very crabby. But the Chinese buyers are very selective - they only want certain ones. But what they are looking for: Old? Male? Pregnant, no algae, really wobbly eyes?
So what's the inside scoop? And do have a similar query to ask of other CHers?