A person who is a smeb is a "snobby music elitist bastard", someone who takes pride that their music taste is diverse and superior than the tastes of someone with limited or bad tastes. They do not often value the opinions of people with limited or bad tastes and are sometimes verbally aggressive in enforcing their points on others. Even though it is an acronym of a series of words, it is also a word in it's own right to describe someone of such a nature.
The late BBC Radio 1 DJ, John Peel. A supporter of alternate and underground music from it's very conception who played whatever he wanted on his show without question to his musical authority. John Peel is an iconic smeb.