A few hot-dog vendors in Brooklyn told the Daily News that business was down significantly, but does that make it a trend? One cart owner outside the Brooklyn Supreme Court says his sales have dropped 50 percent this year — and that he won’t pay the $48,000 for a permit to sell there next year. A vendor in Prospect Park is predicting another bad summer after business diminished 30 percent last season. Can no one drop $1.75 on a hot dog anymore? What does this mean for Mister Softee — let alone Mister Van Leeuwen? If the recession takes our street carts, New York’s culinary scene may never recover.