Yes, but I wouldn't really call them fools. Many people have vaguely heard of "mystery shopping" and recognize it as real, but are unfamiliar with how it works. I have an intelligent friend who received a check in the mail, and if she hadn't known a little about shopping through me, she might well have made the deposit. She thought it was probably a scam, but still wasn't sure, and called me to check.
These are difficult times, and it's easy to take advantage of desperate people. When I read about people who have fallen for this, often people with a need for additional income, it breaks my heart. And, it makes my stomach churn. Just disgusting.