I am certainly biased as the owner of two different CMCs over the years, but the quality of the CMC body fiberglass is usually very good with a small number of minor issues, easily fixed.
After that and as Alan mentioned, the quality of the finished car can vary widely depending on how good the shade tree builder was and how much they wanted to spend. I have personally seen more than a few CMC cars that are truly show-car quality with lots of custom touches. I have also seen a few that looked like someone needed to care a little more about the finished product.
All you can do is check out the car in person and then decide what needs to be done to it to get it to where you want it to be and how much that’ll cost to get there, the same as any other builder and their cars, like VS, Beck, IM or JPS.