Had one for years, maintenance free with the exception of changing the filters. I have never found a trace of spray dust outside of the spraying platform
I know that someone has mentioned on a previous thread on these booths that your supposed to stick the end of the pipe out of the window and not as the picture shows, blowing in your face, I would have thought that was obvious, but there again.......
To make the whole setup really convenient to use mine is connected to a permanent shower vent through the wall with a flap on the outside to prevent air (cold in winter) coming back down the pipe into the workshop when the unit is not in use. To date there are no signs of spray dust on the outside wall either.
Paul.