That is a great question.
Some are more easy to identify than others. I made a post about a few things that I look for in identifying shills. I think that it is important to know when you run across one so you can defend yourself against them. I was just blocked by one. I was told I was causing drama. If making a list that helps point out shills is drama than yes I am causing drama. Something I should have added to that list is trying to censor what a person has to say. Free speech is just that. Over all I think trusting your gut is a must. If you can think of anything you've come across please let me know and I will be happy to pass it along.