From getResources 1.2.0 (snippet.getResources.php):
$criteria = $modx->newQuery('modResource', array(
"`modResource`.`parent` IN (" . implode(',', $parents) . ")"
,"(`modResource`.`context_key` IN ({$context}) OR EXISTS(SELECT 1 FROM {$contextResourceTbl} `ctx` WHERE `ctx`.`resource` = `modResource`.`id` AND `ctx`.`context_key` IN ({$context})))"
));SELECT 1 FROM {$contextResourceTbl} `ctx` WHERE `ctx`.`resource` = `modResource`.`id` AND `ctx`.`context_key` IN ({$context}))will never return any record so EXISTS() will always true.
