This one is actually quite simple as there are a few telltale signs that the person you are talking with about building your house is a true builder or the contractor salesperson type.
It starts with the handshake. Do their hands feel rough like they've spent years on the job site or are they soft?
The next way to tell is by the vehicle they drive. Do they own a work vehicle?
If you are still not sure after those two questions- this will be certainly tell you- Ask them if you can see their tool belt.
With regard to Kuszmaul Builders answers these questions, I'll be happy to shake your hand when we meet. The proof of the last two points can be seen below.
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So does hiring someone that meets these three criteria guarantee you a good job, certainly not, but it can go a long way in indicating to you if you are dealing between someone who truly knows building and someone that is "telling" you they know it.