The biggest privacy vulnerability for dating services is a simple reverse image search. The majority of users use the same images for their dating service as they do for every other social network.
Once you've found their Twitter/Instagram/whatever, then you have a name. Now you have their Facebook profile.
Also, once a person gives you one bit of information it becomes infinitely easier to find them.
Especially with the facebook graph search you can do something like: "women who live near me named _____ who like _____ and graduated from ____." And then you have their facebook profile...
I am still sort of shocked that facebook just allows anyone to do this.
To be fair, that is (was?) the entire point of facebook. Allowing people to connect and answering the question "Remember that girl "Jane Doe" from college, what is she up to?" was basically the killer feature.
That's a far cry from "show me all female friends of my friends near me who are single and like the walking dead" or "all males in nyc who work at X company and use tindr app".
Facebook gives zero privacy to anyone using it. If I walk into a coffee shop and see someone interesting working there, I can just run a graph search and page through the results until I have their entire life history online.
Wow I didn't know you could search apps too, it appears you can see all apps someone uses "Apps used by <name>". I guess that could avoid the awkward moment on dates... "Hey do you like Candy Crush?"
The problem of reverse image search is also magnified by Tinder only allows users to display images from their Facebook profile on their Tinder account.
Once you've found their Twitter/Instagram/whatever, then you have a name. Now you have their Facebook profile.