Drush css-js cache clear error
The latest dev releases of Drush (both 8.x-6.x and 7.x-5.x) now provide a better error message when attempting to select a specific cache type (e.g. css-js) without first selecting a working Drupal site.  c.f. http://drupal.org/node/1954552

Note also that when selecting a Drupal site, cd /path/to/drupal/root only works if settings.php is stored in a directory called "default".  Otherwise, you will need to instead cd /path/to/drupal/root/sites/mysite.com before using drush cc css-js.  You can also use the --root and --uri parameters, e.g. drush --root=/path/to/drupal/root --uri=http://mysite.com cc css-js