Back when French press was the only way most people brewed at home, the common advice was 'use dark roast, the stronger the better.' That was a mistake. Dark roast in a French press gives you a heavy, bitter cup that tastes like burnt toast and hides any flavor the bean actually had. It's why so many people swore off coffee or drowned it in milk and sugar.

Another early miss: people treated French press like a drip machine. They used a medium-fine grind and let it steep for five, six, seven minutes. That over-extracts, pulling out bitter compounds that make even a good medium roast taste harsh. No wonder the stereotype was 'French press is for people who like sludge.'