It’s that time of year again when New Yorkers debate how much to tip the – deep breath – doorman, super, handyman, locker room attendant, trainer, baby sitter, dog walker, beauty salon, cleaning person, day care center, garbage collector, mail carrier, paperboy and parking attendant(s). Sewell Chan, the Times’s Man on the Web, has tied himself to the tipping post with a 1,780 word monograph on the subject, largely sourced from Doorman, a book by......