I assume you are talking about personal website ads. I have seen many such websites that have links to "friends" or "I do doubles with" links to others' Profiles.
"Friends" are very often Providers in the same "category" (similar rates, similar touring, similar services). If you like Mary, then you might like her friend Susie. And Susie has a "friends" link back to Mary. (Damn: there's a word for the whole links to each other in a ring, thing.) Some "friends" links are just placed there via a consolidator and the girls might not really know each other personally.
I have seen websites that provide links to other Providers that the do doubles with the Primary. Duo claims usually sounds more legit and real, to me, and the girls have probably (but not always) met under intimate circumstances.
But the primary Provider usually has a Profile. If she has NO PROFILE (yet), it is reasonable to assume the friends and duos claims are legit but, as far as they go, they are not as reliable as TER reviews. If a duo partner is well reviewed, you can ask her if she really does duos with the non-Profiled primary but that's getting a little sketchy and she might consider you a time waster.
Exactly who or what ad are you talking about?
Posted By: lessdoitagain
Why do ladies allow their girlfriends to share the link to their profile page? Is it to let potential clients know that the friend without a review/profile is legit? It can be confusing when the person in the ad doesn't match the profile when you click onto the link for the review and profile page.😀