While attempting a DB export from a Drupal site via drush, I hit an obvious problem.

OS X's mysql and MAMP's mysql are not equal.

to access MAMP's mysql from the command line (and drush), you can create a .my.cnf file in your home directory and save the contents as:

[client]
user="root"
pass="root"
port=8889
socket="/Applications/MAMP/tmp/mysql/mysql.sock"

giving credit where credit is due: Davy Van Den Bremt at drupal coder, and Josh Koenig from Chapter Three.