It would help, except people don't read SPAM (Score 1)

If those people were a study group then no wonder they read their SPAM, they probably knew it was from the thing that they were /paid/ to do, so they must've read it because they thought they wouldnt be paid otherwise, or simply because they felt bad to take their money and not read their emails.
Normal SPAM isn't usually read, it's just discarded, so... :P