I have painted almost every piece of train stuff that I own, either because I bought undecorated stuff, or I wasn't satisfied with the factory paint. I'd guess that I have about two dozen pieces of factory painted rolling stock, although most have been modified somewhat, and, of course, touched-up somewhat. Even if I keep the factory paint, I often change the car number. I just stripped all of the lettering and weathering off a Red Caboose PFE reefer that I built a couple of years ago, as I want to back-date the paint and lettering scheme. I used to do a fair amount of custom painting, so it's not really that big of a deal.
Wayne