Well, as a NASCAR builder, I go for the best paint job possible. As a couple of members here know, I also like to weather some of my cars, which really isn't that hard to do. I agree that the cars (mainly the older ones) don't have showroom paintjobs, but in NASCAR the cars recently have had amazing paint. I personally don't have easy access to 2-part clear, so 99% of the time I'm using Tamiya clear, which is ok, but it's not going to look pristene. I built a Buick a little while ago and had a buddy shoot some 2-part clear on it, and it looked like a mirror. If you have any questions as far as weathering goes, let me know. I have a few tricks up my sleeve...... Basically, I try to get the best paint possible, unless the car's really banged up, like a car from Days of Thunder! Hope this helps.
Jamie