You pull a shot, and it looks right—gorgeous crema, decent volume—but the smell is… meh. It's like the coffee's shy. Before you blame the beans or your machine, let's run a quick stress test. This isn't lab stuff; it's just a systematic way to isolate one variable at a time. You'll need a scale (if you have one), a timer, and a notepad. Change one thing at a time, not everything at once.