About the only time my airbrush itself could be blamed for problems that happened when applying a clear coat (either flat or gloss), it wasn't the airbrushes fault, but mine. At least once, I've failed to clean my brush properly and flecks of dried paint were deposited on the model's surface along with the clear. And early on, I had water come out of the airbrush, which really screws up the finish. Cured the first problem by ensuring that the airbrush was properly cleaned when changing from pigmented paint to clear and installing a water trap in the air supply line. Another problem I had that wasn't the airbrushes fault was the natural humidity in the air which turned the clear coats milky or white. About the only way to get around that is to either not paint when the humidity is high or purchase a de-humidefier. The dehumidifier is a somewhat expensive route to go, but the decision in my case was based not necessarly on my modeling but the fact that the high humidity was causing other problems in my basement.