Must deep-roasted coffee beans taste bitter? What's the taste of scalded coffee beans?

What is the taste of overdeveloped coffee beans and scalded coffee beans? The overall flavor of a normally roasted coffee bean should be pleasant and there will not be unpleasant flavors such as bitterness, bitterness and so on. Sometimes, the over-play of coffee beans, that is, what we often call medium-deep roasting / deep roasting and other coffee beans, its flavor is more inclined to caramel reaction, black flavor such as cocoa, dark chocolate, smoke and so on. But the scalded coffee beans are more of a smell of charred wood, because the surface of the coffee beans has been completely carbonized and all the flavor molecules have been lost, and this kind of coffee beans have the lowest market value and are generally used in the production of instant coffee.