Australian flies are so much worse than the ones I've encountered elsewhere. It doesn't matter if you brush them off: they will hover just out of reach for a few seconds and then settle back down on you. Once you attract a cloud of flies (and you will) there is no getting rid of them. You can run for blocks and they will stay put for the ride. And they spend all their time trying to get into your mouth, nose and eyes (people say they are after the moisture, but EWW).
The ones in the picture stayed with us for the whole ten minute walk to the beach (yes, this is another photo from last weekend), and settled down happily on our stuff to wait for us while we went swimming.* Then they followed us all the way back to the house.
* Australia is also the only place I know of where huge numbers of flies hang out at the beach. That is seriously weird, guys.