If Ray Haffner is Red John, then why would he pay someone to bug the CBI?  He had permission to be in the CBI office anytime he wanted.

He could have bugged the room himself, so why would Red John run the risk of exposing himself by hiring a private eye to do something he could do himself.  Further, the bugging makes no sense at all any way.  If the private eye were to listen in on the conversations in the CBI, she would put two and two together and realize that the person who hired her to bug the room is the suspect the CBI is hunting. 

Therefore, in my opinion, Red John is not Ray Haffner.

LEFT HANDED AND POINTED OUT A LITTLE TOO OBVIOUSLY. It almost seems like they are all pointed stuff out on purpose. Like they all know what Jane is looking for. Anyway he is giving off the vibe but he lacks confidence I feel

Hiring the P.I was complete genius on RJ's part. I can't be the only one who thinks she looked a lot like Summer, coincidence? I think not, which means that RJ would have to be somebody who knew about Cho and Summer. Also, whether they caught the bug or not RJ would be in a superior position to either lead Jane into a trap or have the CBI office bugged. Correct me if I'm wrong but didn't Haffner still work for CBI during that time?
Haffner also fits all of the descriptions we have on RJ thus far, he is my number one pick for being RJ.

The tattoo is not actually a tattoo its a scar. a scar from a tiger, and the secret organisation know this hence 'Tyger Tyger' and Jane was a carnie/circus man, and circuses have tigers. Anyone who knows about the 'Tyger Tyger' is a member of undercover agent from the 'secret' organisation

Spider, spider! Haffner bright.
In the stiles of the night,
what immortal bertram or eye
Could frame thy fearful smithry?

1.He has arachnophobia(he is afraid of spider) and RJ has acrophobia. Well, RH is phobiac just like RJ
2. Have you seen anyone calling Lisbon by first name Theresa, Only RJ and RH has done it. 
3. He kills too much that he thought of benefiting from his own murders, hence started separate agency.

I know Haffner was pushed as RJ during 6:05, and normally that would lead me to suspect someone else, but in this scenario, i'm actually going to go along with it. My reasoning is:

1. He's a perfect physical match for Red John
2. His walk is a perfect match to RJ
3. The way he grabs people's shoulders is a perfect likeness to the way RJ did to PJ at the end of Red Sky in the morning.
4. He has a genuine phobia
5. With PJ and the other 4 suspects, their relationships are more of a mutual distrust, PJ and Haffner flat out loathe each other. 

I know some will wonder "If Haffner is RJ, why hire someone to bug the CBI office?" Simple. Distraction. You wouldn't want to draw attention to yourself if you were a notorious serial killer, so have someone else do it to draw attention away from yourself.