Adding to the list:

If someone exaggerates in her compliments or appreciation of you in speech, and it is not matched by her actions, watch out. Some people are more expressive and intense, so something that sounds like exaggeration is not always insincere. However, if her behavior does not match up with her words, that is a fake friend. If you or one of your friends catch her giving you dirty looks/ rolling her eyes, or she acts in any way that is contrary to her words, that is a fake friend.

Look for any inconsistency between her words and her actions.

Thank you for opening this thread.