Yeah, pretty much this. Some have the obligatory "free if fake pics" in the ad. Basically, it is the same girl but pics either touched up or about 10-15 years ago. But if you really look closely at the pics in most ads and do some image searches, a lot of them use stock photos from Asian porn sites or generic escort ads around the world and often even within the same ad, they are pictures of different girls because they think all us white devils can't tell the difference.
One other thing about them that's just food for thought. Whenever you see 3-4 ads in a city for these girls that have similar wording, they are almost 100% being "managed" by an old Asian madam. It's a little sketchy.