Each tool works a little differently, depending on the site. You can to all of them from the "Predator Alert Tools" menu on her site, and the list is growing. This is one of those things that work better the more people use them, as well.
An example of how it looks for OkCupid:
Some also do cross-reference with sex offender registries, and all also have a user-submitted warnings function -- basically, a way to make the background whispering about Missing Stairs a lot more visible.