I've had pretty good luck using
Meguiar's Deep Crystal Polish by hand on my black 2005 GSX-R100. It took out most of the swirls on my fairings. I think I will try something a little more aggressive with a DA to get the rest out though.
Like someone else mentioned, you might being going too aggressive and introducing swirls/marring. Try the least aggressive product you can and try multiple passes. I'm going to try Megs #80 and possibly #83 soon and see what happens.
Some people say use
PlastX, but I'm not so sure of that. Yes, the fairings are plastic, but the paint is paint, not plastic.
The problem with motorcycles is the paint is pretty soft on the fairings and it's almost impossible to keep the paint flawless if you ride it on a regular basis. There is so much debris on the roads and motorcycles just tend to eat it all up. The other thing is your clothing will also rub on some of the parts including the tank, so that's pretty much a losing battle to keep the tank swirl free. Best thing to do is get it looking good once and do your best to keep a good coat of wax/sealant on there to keep from getting jacked up again.