Someone who's vulgar has bad taste, and could also be called unrefined or unsophisticated. Your snobby neighbor might mutter about your family's vulgar taste if you paint your house with hot pink stripes.
From the Latin vulgus, meaning "the common people," vulgar is an adjective that can describe anything from the sexually explicit to the merely ugly and crass. A crude joke could be considered vulgar, as could a breach of etiquette at a dinner party. Your dad might love the lights and glamour of Times Square, while your mom finds all the brightly colored corporate logos to be vulgar.