I know we aren't talking about apps right now, nor encouraging the use of them but I thought I'd share some things I deduced after years of using them
1. If her profile pics are all at angles, full make up, and/or always has filters on, she's hiding her true self. The more honest girls will often times include 1-2 photos of herself without any of this crap. They'll complain about guys using old photos in their profiles (valid point usually) but then deceive you with all of the above.
2. If all of her photos are all group pics and she doesn't specify which one she is, she's the ugly one
3. The most eye-rolling quote they add to their profiles is "If you can't handle me at my worst, you don't deserve me at my best". To me, it's akin to girls almost universally hating pictures of men holding a fish.
4. If they don't include a single photo of themselves from head to toe, they are absolutely hiding something.
5. Perhaps my biggest annoyance is girls who post photos where you can ONLY see the back of their head. Girl, I ain't here to date the back of your head. If you can't even post a single photo of your face, apps are 100% not for you.