@humanetech
I often think that too, and with many things - I'm stunned / it's stunning. How they are actually quite clean / cleaning themselves always for optimised flight and even if their food by nature is the rotting kind still they do quite well !
If it bugs you (hehe) then yoo can catch it in a empty jar really easily by slowly moving it over fly, and then newspaper underneath....

Especially when they sit near a light source (I do this before bed sometimes if there is 1 inside, and failing that turning lights of with just a side lamp on means I know where to catch it :)