Unlike the other ads on these pages, Shelby's are decoys. And the models -- all adults -- agreed to pose for them.
It's part of the organization's new initiative called Demand Tracker. YouthSpark provides support to juvenile victims of sex trafficking and those at risk of exploitation. But executive director Alex Trouteaud says that just wasn't enough.
"When every day, you are serving youth who have been sexually exploited, at some point you sit back and say what's causing this? Because it's nothing wrong with the kids," he said.
"We really felt like we owed it to the youth that we worked with to work upstream and start doing what we can as an NGO to address the exploitation that they are being faced with."
Enter Demand Tracker.
It's a simple tool -- an employee, like Shelby, posts decoy ads offering juveniles up for sex on websites known to be frequented by predators.
When a prospective buyer calls or texts the number in the ad, his or her number is recorded in a public, searchable, database.
Callers also receive a deterrence text message warning them that the number has been flagged and made available to law enforcement.
A new decoy ad was posted online when CNN arrived at the YouthSpark office. Just two hours later, it had garnered more than 30 responses. Total number of unique phone numbers collected in the site's four-month history? 12,000.
"Roughly 40% of those are guys calling in from out of town who are flying in," Trouteaud says.
"They'll give us their flight information, they'll tell us where to meet them, how much they're wanting to spend to buy a young person for sex -- hundreds of dollars. So this is a problem of scale."
YouthSpark leaves the follow-up to law enforcement.
Having these phone numbers may seem like a slam-dunk for police. But, it's more complicated than that.
The database only confirms that a particular phone was used to call or send a message to a decoy ad. It cannot provide confirmation of who made the call or if the owner of the phone has ever completed an illegal transaction. It also can't differentiate between intentional calls and misdials.
Anyone whose number appears on the site has the option to click the "remove number from list" button which will remove the number from the public-facing list; however, it will remain in the database itself.
Trouteaud says law enforcement is mainly concerned with repeat callers as those calls are more likely to be intentional calls to buy juveniles for sex.
What happens with the data?
Demand Tracker is still new, as is access to the type of data it provides. Law enforcement hasn't quite figured out the best uses for the information yet, but they do see it as a value-add.
"It could help in bringing together training curriculum on how to track purchasers by looking at their patterns and habits," says DeKalb County assistant district attorney Dalia Racine. "It could also help with pushing legislation to make tougher laws against purchasers."
YouthSpark's long-term plan is to expand its partnerships with law enforcement entities -- the data could ultimately help those entities allocate their limited resources more effectively and remove more sex predators from the streets -- and from the internet.
They're also partnering with local companies. Companies can check company-owned phone numbers against the database to identify potential predators in their ranks.
Racine says the initiative sends a clear message to predators.
"We are coming after the demand side just as hard as we are after the exploiters and the supply side of this issue. And you are no longer going to be safe behind those keyboards. We are going to find you and we are going to prosecute you."