You never know what you'll get. I had an A&P IA teach me to rivet on the tail of my RV-6A. There were a few dings but he didn't say I needed to redo anything. Then I finished the wings, moved to Flagstaff, and built the fuselage. When I moved the kit to a hangar to finish it up, I thought I'd get a TC in to look before I started in on the expensive stuff. I called the only guy in the area, who showed up, looked my project over, and told me it was terrible - all the dings needed to be repaired with extensive skin patches, I should be using special nesting dimple dies, and so on. I was shocked but I had no experience so I couldn't refute him. He called me the next day and said he'd thought it over and wanted to talk with me. I thought he'd reconsidered how harsh he'd been but, no, he said I had no mechanical ability ("not mechanically inclined" was how he put it) and that I should probably sell the project. I questioned that - if it was that bad would it be ethical to sell?
Anyway, by that time I'd been meeting some of the local pilots and when they heard the story and who the TC was, they surmised he wanted me to sell the project so he could buy it cheap. A few A&P and A&P IAs looked at it and said it was fine. I even got the DAR who was inspecting another aircraft to look at mine and he saw nothing to worry him (later he would do the inspection and made me replace one poorly riveted nutplate). So the plane flew and, while it is not show quality, has given no major problems.
After that incident, I decided that no other building in our area should suffer that. So I convinced the builder of a Lancair Propjet to become a TC along with me. Between us we cover turbine and conventional engines and metal and fiberglass construction, plus we know local A&Ps to give assistance when our experience falls short. Our mission is to assist and advise; when we point out a problem, the attitude is 'it can be fixed, no worries' not 'you should not be a builder.' By the way, the standing joke is still that I'm not mechanically inclined...
My point is that there is no real regulation of TC quality. I'd be willing to bet that if your TC is a builder (the one discussed above was an A&P with no experimental experience) then you'll have a good experience. Even so, there's bound to be a few bad apples in the basket, so be sure to get second or even multiple opinions before you react to what you've been told. That's not a bad thing to do even if your first TC gives you a glowing report; the more eyes you get on a project the more chance you'll have of catching small errors. If you enjoy the building process then you will find that making corrections is as engaging as the rest of building, which takes a lot of the angst of having your work inspected away.
Hey, if a Navy plane pulled from the depths of Lake Michigan can be restored to flying condition, then any small error you make on your project can certainly be fixed.