I love my Iwata and would marry it if the State of New Jersey would sanctify such an unconventional union, but the paint control it provides is only as good as its cleanliness. I've always used cotton swabs to clean my airbrushes, but I always felt like I was leaving something behind.
I confirmed this recently when I purchased a set of small, stiff-bristled brushes on eBay. The smallest is perfect for getting into the tight spaces of the airbrush, such as the tunnel the needle passes through behind the trigger assembly. With my first cleaning using it, all kinds of pigment came out, which you can see in the photo below. I now use the brushes after every painting session, which I believe has allowed me to extend the intervals between my completing disassembling the airbrush and giving it a through cleaning.
If you don't have a set of these brushes I strongly recommend going to eBay or another source and buying them. It's a small investment, but it will contribute to the quality of your painting, not to mention extend the service life of your airbrush.