The lower recirculation fans on 747-400 deliver directly to the fligjt deck. I have seen and smelt whem a rupture vac waste line aft of the lower recirc fan was delivering a lovely odour straight to the flight deck. As for A330 I have not seen or heard of this. I would be inclined to demand having the toilet extraction filter changed and the toilet waste gate and attached plumbing inspected and leak checked. Also note if its only directly after flushing or a consistant smell.....
I have tickets on both of those types.
GP