REVERE – Sarah Fleek just wants to read a book while enjoying a safe ride into Boston every weekday morning, but some of her fellow Blue Line riders have other plans for their commute.”They talk on their cell phones and even have intimate conversations next to me,” said the Winthrop resident.Fleek’s critique of subway rider courtesy has not fallen on deaf ears with the Massachusetts Bay Transportation Authority. The MBTA is unveiling a half dozen subway and bus banner advertisements on hundreds of train cars and buses this week encouraging courteous ridership in what spokesman Joe Pesaturo called “a fun, light-hearted manner.””With ridership at record levels, some of the most common MBTA customer comments pertain to the manners and behavior of other public transitusers, including people who don’t offer a seat to those who need it more; littering; loud cell phone chatter; people who force their way onto a train or bus before allowing others to get off the vehicle first and fare evaders,” said Pesaturo.Blue Line commuter Vincent Marano offered an addition to that list Wednesday – people who “cough and sneeze all over the place.”Riders who force their way onto crowded trains are especially annoying to Michael Scarlata of Peabody.”They show no courtesy to the people in front of them.”The MBTA is promoting courtesy in the wake of its summer efforts to renovate Blue Line station platforms and add six-car trains to the Revere-Boston transit line.