In the scenario I gave, the potential new employer did know about the non-compete and chose not to hire as a result--whether or not the non-compete would actually have applied. How did we know? We asked as I was asked when I was hired at that company.

That said, in lawsuits, lots of people and organizations tend to get sucked in whether they deserve to be or not. The bottom line is that non-competes have significant chilling effects whether or not lawsuits are ultimately filed.