Puckstrology is practiced in some circles of the coffee world. The dark secret world centering around espresso where the line between myth and reality blurs. I am not talking about something mysterious like having your fortune told by a mystic who reads the tea leaves in the bottom of your cup. Those type of diviners of mystical truths might actually know what they are doing - especially if they predict you will be needing a refill of your tea cup. The practitioners of the black art of puckstrology are far more sinister.
These soothsayers look into the blackness beyond a man's soul - they stare into the abyss of a man's spent espresso puck and predict fortune or ruin for the shot just pulled. Taste has no bearing on the facts. The dark wetness of the coffee grounds reveals all. One predicts great extraction based on the imprint of the showerhead screen bolt on top of the puck while another proclaims utter failure based on marsh like soupiness.
A little better late than never terminology clarification is in order. The puck is a term used for the packed coffee in the filter basket of an espresso machine. A spent puck is the same packed coffee after the water is pushed through and the coffee is expressed out into the shot glass or cup below. A problem with the puckstrologer's reading is that it has zero consistency in prediction and even less chance of predicting how the shot will taste.
Soupy, firm, cracked, or stuck to the shower screen - I have seen it all and still tasted good espresso. Long as the stream going into the glass or cup looks right then the shot will be extracted properly and the taste should be fine. Next time you see any mention of puckstrology ask the practitioner to repent and taste the shot - this will usually send them running for a dark cave where they can mine Folger's crystals to their heart's content.