You ordered a beer at a bar or crack opened one at home. How good is the beer you are about to drink? Everyone has her/his own way of evaluating if they like a drink or not. Here are a few things that could help with your beer evaluation.
The most visible sign of good beer. The small bubbles of CO2 that form the foam are responsible for the beer aroma we experience. Thickness and structure really depend on the beer style and ingredients used. Some ingredients (like nuts i.e.) tend to decrease the foam and make it unstable. Brewers use various malts to get great and stable foam. When Staropramen is properly poured into a glass or mug, the foam is rich and velvety, as if somebody poured shaving foam on top.
Oh, lacing! Who would have thought that leftover foam on the side of the glass could be a source of such pride for every single brewer. It is the actual proof that the beer is well constructed. Once a glass is emptied, lacing is a sign of a good beer (and clean glassware for that matter).
To balance a beer means to create an interesting taste without any of the ingredients overwhelming the others. Sweetness and bitterness are the primary beer flavors that fight for the drinker's attention and they should both shine through, especially in a bohemian lager.
This goes without saying. Beer is there to be enjoyed and off-flavors spoil the experience. Off-flavors can be traced to any part of the process: brewing, fermentation, packaging or distribution. As always, better knowledge leads to better beer.
Sometimes it is quite simple. You either like it or not. We will Nazdravi to that!