In today's world, it really is hard to tell if a candidate is a good fit for your open position or your company culture.  You can interview someone all day long, look at their perfectly laid out resume and still ask yourself "Are they right for us?"  I myself have been fooled several times over the years by people who can present themselves very well in the interview setting with all the right answers and a great looking resume then finding out they are a very bad fit for the company.  

Luckily, easy screenings using social media sometimes reveal a candidate's true colors. Social media screens are suggested standard practice for any hire. Make sure to check with legal counsel to understand what employers may or may not consider and say about social media profiles, before and after an employee is hired.

Are They Respectful

Twitter should be the first place you look.  Most users keep their profile public so you can easily see a person's tweets and retweets and who they follow.

-Everyone I work with is an idiot.
-My boss is a pain in the rear.
-I hate working here.

These are all tweets I have seen people post.  They speak for themselves and for me would probably raise a red flag.  

Precision

Does all your candidate's information match from all sources.  A big one is Linked In.  Work history and education discrepancies between Linked In and their resume can raise the red flag.  Now could this just be something overlooked by your candidate?  Sure, but if there is suspicion in the first place this is a good way to help weed out any potential untruths.

Issues With Anger

Many times Facebook and Twitter users use these accounts to voice opinions.  What you are looking for is anger filled rants, threats, vulgarity or racist comments or postings.  Someone active on these social platforms will most times reveal these types of personalities and can be useful in making a hiring decision.

Other personal qualities to watch for include narcissism, nudity, hate speech, violence, excessive profanity, and bad grammar.  Have they talked about being sued or getting someone fired?   

Remember all of the items above are reminders to us all to be aware of what we post on our social accounts.  They can be used in a hiring process and decide the Yes or No decision.