mailing houses that offer guaranteed response rates?

Hello all. I'm trying to get the scoop on two mailing companies that are claiming to guarantee their customers a 1% response rate or they'll re-mail the same quantity for you until you receive a 1% response rate. The two companies I've come across that make this guarantee are WorldProfit Marketing, Inc. (CEO is Michael Larson, not Jeff Lant's company) and the other company calls themself New Life Publications. Their web addresses are mailordermastery.com and newlifepub.com
Anyone who can offer insight or experience with either of these companies would be a huge help for me to decide whether or not I should get involved with them.
Thanks,
Tom