I have NEVER hired a construction worker or plumber that has done perfect week. From carpet guys to installers, there has always been something that was a little bit off or had to be corrected.
...but then again, I'm not perfect and neither are you. We are all humans and we make mistakes. I think the BIGGEST difference between whether a company is good or bad is not whether or not they make mistakes. It's about whether they are willing to fix their mistakes.
As a homeowner and employer, you are entitled to a good job. You don't have to pay until the work is done and, many times, this encourages workers to do it right.
Never pay your workers the full amount when they have just finished. First, go over the work that has been done, share your concerns, get things fixed and then pay them.
Everyone makes mistakes; will they make it right? - Rejoicing in the Present