Bar trends come and go. One day, it’s wannabe Tom Cruises juggling brightly colored shakers, the next it’s a hipster putting 19 different kinds of bitters in a glass. But one American drinking institution that will never change is the humble dive bar, that dark, dank, slightly disreputable den of sin where ancient old men and wily young pool sharks come together under the banner of stiff drinks, good company, and a moderate amount of danger.