Is an actors’ public persona reliable? Authentic?

Alan Chenkin, Learned about celebrities reading magazines at the supermarket checkout
 
“We are each responsible for our own life – no other person is or even can be.” – Oprah Winfrey.
Most actors have a public and a private persona. The public persona is their brand, how they show themselves to the world, and how they get more roles, recognition, and exposure. Good actors have a consistent and reliable brand, so endorsement deals, roles, and commercial work can have their consistent star power on their packaging. An actors private persona is when the paparazzi have gone, they are at home or in repose, and they are not “performing” or being in character.  Having a “private” persona means they can rent hotel rooms, cars, and charge meals without revealing their true identities.  It allows them to have a life outside their famous identity.
From the Web:
A professional actor will have a consistent  brand.  They will be in character, have measured behaviors (as their fans come to expect), and deliver reliable performances and numerous public relations work (appearances) for their studios/TV/Stage gigs.  Promotion is an important part of the business, and most professional actors have a team of people managing their social media, Paparazzi, and public relations.
When you see an unreliable actor or Diva, you have to wonder if that is their public persona, a publicity stunt, or are they cracking under pressure?  For Example, Tom Cruise excitedly jumped up and down on the Oprah set.  It was unexpected, and got a lot of press for the actor.  
Thank you for reading my blog!  Feel free to like, upvote, and share!
 
Expanded and edited from my answer to this question on Quora.