Well I did my filter on Friday and it really was disgusting the amount of grey dust which came out, must be 2 years since I last cleaned it It definitely works better now, should I warn the cleaner incase she starts sucking up carpets?!
I don't have a dyson but I notice a huge difference in suction when I clean the filter of my bagless hoover. When I can no longer tell that it's supposed to be blue, it needs a wash