Usually inexperienced founders err too much on the side of paranoia. About keeping their idea secret for example. But they err too much in the other direction when hiring executive teams. "C-suite executives" can be really good at tricking you.

The most common trick they play is seeming competent when they're not. This is arguably the most important skill within sufficiently large companies. (Which is why startups can exist at all.) But there are darker tricks too.

When hiring a COO, for example, it's worth asking "Could I imagine this person conspiring with investors to force me out?" Maybe 99% of the time the answer will be no. But if you find you pause before answering, you may want to stop and think about that.