Aromas, both good and bad, tell a lot about how a homebrew was made. Picking out the yeast character in a smell will tell you if the fermentation was healthy or not. Poor sanitation leading to bacterial infection can be detected on the nose. Even the length and vigor of the boil will contribute different aromas to the final product. Being able to identify the different aromas in beer will help you improve your process and fix problems that you find in your homebrew.
'homebrew troubleshooting' on Serious Eats
Beer clarity can be difficult to achieve, but there are a couple of steps you can take that will get you on the road to clearer beer. The haze in homebrew comes primarily from two sources: sediment in the bottom of the bottle and soluble proteins suspended in the beer.
Everyone from the first-time homebrewer to the professional wants each batch of beer to be better than the last. I'll be addressing some of the common problems that homebrewers face in this troubleshooting series. Today we'll tackle head retention and under-carbonation.