NDAs and contracts that you should never sign
… clause which forbids you to hire anybody who works for the company that is making you sign the NDA. Presumably, they think that while you are visiting them, you will hire away all their employees and put them out of business. Well, you know what? If your employees are so eager to leave, that’s your problem, not mine. You need to keep your employees loyal by treating them well, not by creating arbitrary obstacles in their career.
So if an employere wants to make sure that their employees don’t end up being the competition make the work enviroment and the work so compelling that employees don’t ever want to leave.