Sorry for reviving this thread but ...
I think I have the solution on this one.
PREVENTION and CURE are two very different things. To PREVENT hazy white spots / frosting, you should spray in the hot sun / air-conditioned room, etc etc etc. Everyone already knows this.
TO CURE (ie. remove) the hazy white spots / frosting, here is what you should do.
1. Put model kit in air-conditioned room.
2. RE-SPRAY TOPCOAT, at a distance from the model so that it falls like mist.
3. Wait for an hour, turn off the air-con.
4. Wait for 6 hours, open the windows and doors of air-con room.
Presto, all the frosting = gone!
Like hiccups, there have been many suggested solutions to REMOVE frosting. I have tried most of these myself:
A. "Spray some Future on it" --> does not work. the model becomes frosty and shiny, is all.
B. "Spray some Future mixed with flat base on it" --> does not work, but has slightly more "covering" effect than A. the frosting is still visible.
C. "Use Tamiya polishing compound" --> did not work for me. supposedly worked for someone on Plamo, who knows ...
D. "Strip the paint, re-prime and re-spray" --> this is not a solution. this is an irritating person who thinks he is being helpful.
in any case, my solution above definitely works. hope everyone avoids this problem, but if you do screw up, know that there IS a cure ...