Spray painting wouldn't be a bad trade to get into at all. But like with any job, if someone can do it cheaper they usually rush and alot of "ahh she'll be right" goes on. If someone comes in and says 1/2hr is all that job should take (i am 2nd yr apprentice auto elec), all the things get done to make that job work, but the planning and finishing touches just go out the window - You do your best, but 9 times out of 10 you can come up with a better way of wiring something up if you have a think about it - then if you were to use a generic base wiring idea you have set in your head.
People find that the cheapest price usually bites them hard.
Cheers
Sumo