"Publicans" in the New Testament are ostracized and hated, and Christ gives them the special attention all the ostracized receive.
And it came to pass, as Jesus sat at meat in the house, behold, many publicans and sinners came and sat down with him and his disciples. And when the Pharisees saw it, they said unto his disciples, Why eateth your Master with publicans and sinners? (King James Bible, Matthew 9)Calling the owner of a "public house" or "pub" a publican must be a pun based on the various references to publicans in the Bible. (By the way: H. L. Mencken in the 1930s, according to The American Language II, thought the American word for pub was "saloon"; in 2012 in America it's almost certainly a "bar.") In the Greek bible these people were τελῶναι (/telonai/, related to our word "toll") and in Latin, publicani. They were "tax farmers"--people who extorted from the population a set amount for the Roman government's tax revenue, and kept any surplus for themselves. "Publican" has been used often as a general term of abuse.