Usually a Ricky Martin appearance means hundreds of screaming fans, at least. Such wasn’t the case Tuesday night when the singing sensation stopped by the White House for a private tour and a quiet chat with President Clinton. Among the topics of conversation were the books and paintings in the Oval Office — and then a meeting with Clinton aide Maria Echaveste. Martin, a spokesman for his native Puerto Rico, expressed his concerns about U.S. Navy bombing exercises on his country’s island of Vieques. “The substance of the conversation that he had was with Maria,” White House spokesman Joe Lockhart said in a statement. “The visit with the President was social.” In other news of Ricky, he told TV’s “Access Hollywood” that he and Mexican TV personality Rebecca de Alba have broken off their relationship — but that they will remain friends.