Control Views Bulk Operation messages? For my purposes I don't need these types of messages:

2 rows processed in about 261 ms:
Performed Email Reviewers on user joren1.
Performed Email Reviewers on user joren5.


I don't want to hide messages in general. Is there a way to specifically target messages from this module, or specific messages at all?
You can uncheck "Display processing result" in the VBO settings (in the edit view UI).

VBO for D7 stopped generating that many messages in latest -devs (after beta1). It now only shows one message: "Performed $operation on $count items."

That is something that should be backported to D6, there's an open issue for it.
In general, you can't affect those, the module is just calling drupal_set_message (usually in _views_bulk_operations_execute_finished()).