Pouring a beer is an art form that most bartenders take for granted. The goal of a good pour should be to get as much liquid in the glass as possible. Foam or “head” correlates to about 1/4 of what the actual liquid is. As you can see from the picture, the perfect pour should contain beer to the brim. Even as a beer snob, I still understand that the server has to carry the beer and thus an 100% pour is nearly impossible unless you have skilled people at all areas. One can judge how good a bartender is by how seriously they pour their beer. Cup tilted with the tap pouring strictly on the side of the glass opposed to into the liquid is key. I’ve seen some Guinness “marketing” beers that say the perfect pour should have some head but I’ll never trade liquid for foam. I rarely see good pours nowadays but it’s still something to keep your eye out for. And when you do see it, make sure you complement the bartender.