Advice on Hiring

Don’t hire people about whom you have doubts. 

One will make plenty of hiring mistakes during one's business career by hiring people about whom one had no doubts, but who, nevertheless, don’t work out. 

But, the failure rate on people about whom you have doubts is far higher.

Trust your doubts, especially as you gain hiring experience.  The best "gut" is fallible — one will hire people who surprise one by not working out — but still one's best guide.