There are a lot of really smart C# programmers out there... but there are a lot of subpar C# developers out there too, especially outside of Silicon Valley.

I've had a boss who brought in at least 60 people in (while I was there) for an unsupervised (unless you had a question) 60-90 minute test, where he'd leave them alone, let them google, etc, but would sit down and discuss what they did and why afterwards, and the amount of people who couldn't get past the first FizzBuzz question was pretty high.

Those that got past that, the number who didn't know the basics, like what an Interface was or how they worked (or how you're not supposed to write implementation code directly into them) was higher still.

And these are people who say they have 5-15 years of direct experience on their resumes.

I'm not a huge fan of tests and I do tend to struggle myself, but not that badly, and not when unsupervised.