Here's my update:
I've spent $24.76 and earned $39.93. My daily CTRs have ranged from .05 - .10. I didn't earn anything from advertising a background check product, but I made two sales for a fitness related product. My targeting wasn't very good for the background check product, but I think this is a product that could work.
Here are my thoughts thus far:
POF has huge potential right now! Tissa gave us a great tip here. The site has a lot of traffic and you can buy 15 cent CPMs all day long.
CTRs are going to be low so get very creative with your ads.
Don't waste your money advertising your people search engine. Of course with the current MyLife issue this goes without saying, but even with the replacement a buck or two per lead won't cover your advertising costs unless you can get some crazy CTRs and conversions. If you can pull this off I'd love to see your ad.
I wouldn't advertise the business opportunity either. Remember that people on this site are looking for a date not a make money online opportunity.
Even though the demographic targeting is excellent, remember that it's not keyword targeting so find offers with wide appeal to your target audience.
I mentioned this in a post above, OfferVault is a great site to find various offers that could work here.
-Chris