If you have a dusty cloudy look it's because you made a mistake while varnishing. Many people screw up on their first time out with matte varnish because they're not aware of some of the difficulties with its use. You shouldn't be using matte spray when it is cold or moist out. Cold and mositure affect the way that the particles of varnish interact with the air, and will cause it to become cloudy and ruin yor paint job. Spraying the gloss varnish will only make your miniature shiny, which most people tend to think looks a bit amateur, so I would avoid it. I've heard that there are ways to correct bad matte varnish coats, try asking about it on warseer.com. Good luck!