how does the host quickly win the trust of all the pilgrams?

The host, Harry Bailly, wins approval and trust from the pilgrims by being a gracious host. He gives them food, lodging and drink at the Tabard Inn. As each pilgrim comes in he loads them up on alcohol. These pilgrimages were sort of vacations as well. Harry offers his services as a guide. The pilgrims like him because he is quick witted, jovial and generous (the pilgrims liked free things!) The pilgrims are not the most organized lot so Harry Bailly says that he will get them to their destination.