If it worked word would have long since spread and agents and agencies would be doing it. It's extremely cheap to do email blast advertising and I've known several agents who used to do it. "Used" to would be the key word in that sentence since the leads they received were garbage.
The "better" lead companies will not allow their affiliates to email spam - that says a lot.
During the period that I was using this type of lead, I wrote 38 policies. Its been 1.5 years since I've used them and 20 of them are current customers. 21 of them bought short term medicals and 2 of those converted to permanent policies. I've also received referrals from these customers.
So, what do you say to that?