somethin i read up on before i did my silverado's.
"the universe has a way of balancing itself"
Typically, a spray gun is necessary for any automotive style paint. A brush will leave streaks and spray cans aren't generally going to give you a high quality and durable finish like true automotive paint.
I had my door panels painted by this website www.bosspaint.com and my door panels turned out great. The paint hasn't faded or chiped at all.
regular spray paint is the worst way to go i did that with a pickup i had. At first it looked good but a week later it looked like crap.
sanding or the primer or you just didn't apply the paint in thin coats because mine is going on 11 months and still looks great.
I don't think it was the prep work that caused the paint to scratch so easily. Spray paint just can't hold up to as much wear and tear as real auto paint can.
I agree automotive paint is better but if prepped properly rattle-can paints can hold up really well and look almost as good. I'm going over a year on some interior pieces I painted and have had no issues. This includes my switch plates which are touched all the time.
As fort vinyl panels, there is special vinyl and leather paint available wich is flexible. Ask around in you local shoe store