What does the cleanliness of coffee refer to? Which coffee beans have better cleanliness?

Now the first impression of a cup of coffee is often the most attractive flavor with a high degree of recognition. But the cleanliness of a cup of coffee is also very important. Clean coffee what is the performance of a cup of clean coffee, Qianjie believes that there is no miscellaneous smell, defective smell. And it is clear and thorough. Miscellaneous smell and defective smell generally refer to the generally recognized bad taste. Imagine one.