While it definitely doesn't cure every problem, using spray bombs from the hardware store is probably the least controllable application method. You can't vary the pressure, viscosity, spray amount, anything.
An airbrush, even a very cheap one from China, is the way to go for this sort of application.
That said, I've had better luck using a spray bomb with multiple light coats, especially for things like white that tend to be a bit translucent, than trying to get good coverage in one or even two coats. It also gives you the opportunity to do some light sanding between coats if things are looking a bit too thick in areas.
Paul
