There's a checkbox named "Use default style provided by AddThis" on the settings form.
There's no documentation for this field, but my assumption is that if you uncheck this box, addthis should not load widgetXX.css, however that doesn't seem to be the case.
I confirmed that the drupal module is setting use_use_css option to false in addthis_config, but widgetXX.css is still getting loaded.
Is this a bug? If not, can someone explain what the "Use default style" checkbox is supposed to do?