Depending on what I’m doing, I don’t mind the home owner watching me.
Like when I’m replacing windows. We take out the window without disturbing anything else, which many people find fascinating. They just want to see how it’s done, satisfy their curiosity. After they see it, tho, they usually go away.
When painting or doing drywall work, they usually find themselves quickly bored and leave the work area.
Whenever using power tools, I always point out that I have eye and ear protection, so they may want to exhibit caution. That usually results in them leaving the work area.
Now, if the person is trying to engage in prolonged conversation or nitpicking how I’m doing something, I may react in a couple of different ways. If they’re nice, just too chatty, I say something aboout needing to concentrate. If they’re critiquing my work choices, I may inform them that this is what it takes to get to the finish job they want, so just hold the complaints (which are usually totally unfounded, based on ignorance) till the job is finished. With some people, I bluntly tell them it will cost more if they don’t shut up. Usually doesn’t get to that point, but I’m the one doing the work here. If I didn’t know what I was doing, I wouldn’t have bid the job.
So, it all depends on the home owners attitude, basically. Also, this is in response to what I do. I’m a perfectionist and very good at the things I do. Unfortunately for people like me and Dances, there are some jerks in our field. This makes it hard for all of us.
To sum up: if you know the worker is good (and why didn’t you get references before hiring him if not?), just let him do the job. Satisfy your curiosities, by all means, but please don’t hamper progress on the job.