Some of the ads on here make statements like the following:

"I accept Date-Check, Preferred411 & TER Whitelistings."

What exactly are these, what information do they ask you for, and is your privacy safe if you register with them? Any idea which is safest? I assume that date-Check and Preferred411 are similar to each other, but what is TER Whitelistings? Is there a monthly fee to be listed with any of these services?

Thanks for any guidance you can give me.