Raising new questions about how thoroughly CBS performs background checks on contestants for its reality shows, published reports said Monday that Justin Sebik, booted off Big Brother last week after he held a kitchen knife to the throat of another contestant, had been arrested five times in Bayonne, NJ--three times for simple assault. Each case was eventually dropped. In an interview with Tuesday's New York Post, CBS spokesman Gil Schwartz accused the Bayonne municipal court of withholding critical information about Sebik. "Certainly if we had had the information that was made available to the press, we might have given some serious consideration to the facts that were represented," Schwartz said.