On sites that charge a subscription, people with malicious intentions can be traced through their credit cards. And some sites offer users ways to communicate with other members through double-blind e-mail and phone call systems that mask real contact information until they're ready to reveal it.
And Brooks noted that online or off, troubling though it may be to accept, people with shady pasts may be looking for love too.
"Statistically speaking, you have to bear in mind that just as you'd meet someone on the street, you can also meet people who aren't favorable on a dating site," Brooks said. "Anyone who goes on a dating site who is wanted as a murderer is pretty dumb. It's pretty unlikely to happen."