Tinder has a secret success rate value for your photos
uk.businessinsider.com
uk.businessinsider.com
A friend of mine also discovered Tinder was returning dates of birth to calculate age client side, so was able to predict other user's star signs: https://medium.com/haralds-notebook/tinder-should-probably-f... It proved fairly effective at getting a reply, as you might imagine. Thankfully he had the decency to explain how he guessed.
The terrifying bit is the sheer volume of data Tinder is leaking -- I would assume accidentally. The swipe % on the images for referrer and referee are pretty bad, but DOB and number of FB friends is enough data that you could trivially locate the person on Facebook.
What else is he doing to your traffic?
Insert retorts about "but it's their wifi" below. It's still scummy. Provide unmodified wifi or don't provide internet on the wifi.
Replacing asinine Hacker News comments with meaningful ones.
It offers a comparison with other users and the average across all of a users photos probably correlates strongly with the mysterious 'Tinder rating ™'