If you have to buy an existing house be sure you talk personally to the builder and look at houses he/she is building now. There are some very good contractors here but a rule of thumb is that if they don't have their own trusted crews that they use regularly don't bother.
When we built our house here we were at the job site almost every day. We had an excellent contractor but there is no substitute for being there yourself.
I would be comfortable buying a house built by our builder because I know exactly how he consistently builds each house because he has the same people build each house. That can?t be said of most builders.
As a rule of thumb if you want it done right you better be there watching them build it. Even now with all the new code requirements I am seeing things done by other builders in such a way as to put the house at risk.
If buying I would only look at custom built homes that were built for a owner for personal use. Never buy a ?spec? home?.
My suggestion is as a general rule don?t buy a house already built. Go buy a nice lot with at least 30 feet elevation, carefully select a builder with his own crew and be there when it is built.