How can I see the query that's being run?
The views_plugin_query_default class has a query() method that will take the parameters currently held in the object and provide you with a standard SelectQuery (un-executed of course).

Since the SelectQuery class implements the magic __toString() method you can then cast it directly to a string, which will be the SQL query itself:

$select_query = $query-&gt;query();
$query_string = (string)$select_query;
dpm($query_string);