I'm not sure that I agree. My (very...) modest airbrush would do a guitar or bass body, no problem. It wouldn't suit painting a car, but folk use systems of the sort for motorbike fuel tanks, or crash helmets, and much more. I think you'd get better quality of finish and coverage from a half-decent airbrush than from a cheap paint sprayer. Unless you're going for mass-production, of course, in which case a spray booth could be set up. I use my airbrush in my modelling 'den', with no need for extra ventilation; just a large cardboard back-screen. I'll see if I can find a photo...
My Dad made toys for Christmas, but hated having to paint them. One year, it was flat-pack dolls houses; I went to help him with the spraying. He had a compressor and gun set up in the back bedroom. Kitted out like astronauts, with a full mask, 'charlotte', long gloves... One squirt of the gun and one could see nothing; all was a dark green mist filling the small room. He'd rigged 'ventilation' of sorts, with a pipe going up the gutter down-pipe, so the paint-charged air was shot upwards. Several houses down-wind were doubtless surprised to find green spots on their washing, with no idea of where it came from..! Happy Daze...