I know I know... "we can trust the list" but realistically we can't trust anyone.  So I am going with the Red John being a woman.  John Doe and Jane Doe  = male and woman.  Since Patrick is Jane and a male, therefore Red John is a woman :) Also, I remember the episode when Patrick and his father screwed up one family with a very very sick girl by selling a fake healing crystal.  Her blindness could be the consequence of her "survival".. Though she directly might not be the killer, so she has others to do her bidding...

I think that a lot of people assume that Red John is a man and I think it will come back to surprise everyone that RJ is a woman.  First, when Patrick first meet Rosalind, she was serving him tea from a tea set that later shows up on a crime scene where RJ was watching Patrick from another room via video camera. 

And then in the episode where Rosalind calls Patrick after she went with him to identify RJ's body because Patrick thought he had shoot him and she told him that the dead man in the morgue is not RJ, she was the one who also have the opportunity to meet the morgue attendant whose dead body later turns up at her closet after he was questioned by FBI Agent Darcy.  After Darcy questioned the morgue attendant and found out Patrick brought Rosalind to identify the body, Darcy went to see Rosalind and she told her the body in the morgue was not her friend Tagliaferri.  My theory is that when she called Patrick and told him that her friend is back for a visit and it's all just a misunderstanding, we did not see the face of the person sitting on the couch, but I believe the person on the couch was the morgue attendant who does not know that he is sitting with a stone cold killer.  When Patrick showed up at her house after she called, she was playing the piano and claimed that RJ left, but then they found the dead body of the mortician in her closet.  I think she was the one who killed him and she has continued to deceive Patrick because nobody will think that a blind woman is capable of what being RED JOHN. 

starting it streght ahead its about the nacklace & Profiler series references, if Red John was a Member of the group visualize, then maybe in the introduction-episode of Rosa-lind  You see that she have a nacklace on & somhow i think on its is the sign of visualize, also the blindless & even from a symbolic point of view  ther is such a darkness behind her, also the Red John sign is very contradictionary-amblivalent, yeah dialectic its a happy face but because of  floatinng down its gets a touch of tears on eyes which express sadnes, so Red John have interest in this , &  as female if thinking from start a female because of nature is so much capitvated & attracted by Jane & like many before said it would be fantastic to throw away all attention to that male-cantide  & this remind me realy on the case of  Jack & Sametha in Profiler, funny its like if like so to speak translatet or the director & story designer finded this relation very fascinating, Patrick blond in hair & she Red only that this time the Serial-kiler is female & the profiler is male, also the case with the lose family, so many referencec to the series profiler, somhow i think its much intented not only because necassasery crosing of topic-field but the director where very captivated @ this specific history, only what real backround could she have an ex-Profiler && wouldnt it be genious to make this outcome, only the expression of motivation Red John have & toward Patrick Jane is keeped very minimalistic(soulmates), where in Profiler it was very exposed, ah would be greate imu if  Patrick tries to understand more Why Red John choose Rosa-lind(soft, isnt expressed in the smile sign softness & also isnt the Bach music soft) & hark-er(listen)& so spending more time with her & discovering his likening to her & then after she reveals, he start  in joyfull tears crying & happy killing her & she not oposing  & paintig the same smile sign Red John used,on wall above her, CBI coming in & taking him down & all members shoked, yeah what a scene he playing piano the bach music & Rosalind laing on bad  with Sign the Joyfull Smile above her or, Lisbon sees Patrick playing piano, shouding on him but he ist decoupeld an then she goes in room & shocked& start to cry & is showed the sign with rosalind & this end of  ;), this would be a very dark turn but would shown all the Sadness Patrick allways carried  in him besides his gentle & nice appearance & make  put light on all his action ever done, that like he coverd & persuid all time only revange & self-guild & hates toward his arogance cause somehow dead && that would be something

If you watch the "Red John's Footsteps," notice how to tea cup that Jane, Harker, and Lisbon are drinking out of is the exact same tea cup that is shown in the scene where RJ has apparently fled the house where Jane is being held at gun point.

Now, it could be that RJ stole the tea cup from Harker's house, but what if it's a subtle clue from the writers the RJ is, in fact, Harker. If RJ is a man, that's an awfully feminine cup for him to be using. But hey, to each his or her own;)

We are never told where Harker is during the showdown at the country house with Sheriff Hardy. She could have easily been there waiting for Jane. And it would be brilliant of RJ--as Harker--to throw everybody totally off the traill by describing RJ as a male with all the other characteristics she listed, when it is really her all along.

And, being a blind person--with all her other senses heightened like touch and feel--how wouldn't she have been able to smell the scent of fresh paint above her bed after RJ painted the trademark smiley face? It isn't blood above the bed--no killings had taken place at her home at this point (and the post-killing smiley faces are larger and dripping down the wall). It's rather odd, however, how Jane doesn't mention it to Harker. Another thing to point out above the smiley face is that, if Harker is really RJ, they both have smiley faces above their beds--well, at least Jane did while he still lived at his house where his family was murdered.

I personally think it would be awesome if it was Harker, with Jane sitting listening to her playing piano in the episode, seated right next to the person he always searching for. Perhaps I am wrong, but something about the tea cup seems a little off to me. It's a nice subtle hint, I think. But perhaps I'm making something out of nothing. It's the exact same type of tea cup, though. It's odd that Jane doesn't pick up on this because he notices everything.

im not saying harker is red john but people seem to think that when she decribed red john does anyone not care to think maybe red john had that cop stand infront of her and she was decribing him that cop (forgot his name) red johns acomplise is the same short dark hair medium build under 6 foot red john probably used him to through everyone of guard

There are several points which have been pointed out already which I won't rehash but a point I haven't seen mentioned is a minor point yet very significant in my eyes.  In Season 1 Episode 23 when Jane and Lisbon are asking Rosalind about Roy T, Lisbon asks Rosalind if anyone else saw Roy and she responds by saying "I have a Fur Elise-olitary life (or fairly solitary life) but she buts specific emphasis on Fur Elise, (the piece of classical music Jane's daughter plays in some of his flashbacks and something that Red John would be aware of). After making the point she makes a particularly satisfied smile, perhaps at the thought that she is taunting Jane without him realising. Otherwise why would she make such a prominent smile over such an insignificant point as saying she leads a solitary life.  The more you watch it back the more obvious it becomes and it seems like the kind of small, well hidden clue, the writer would include, as opposed to something glaringly obvious

I think Red John is Harker Rosalind. I think she is because if you were red john what would be the best disguise? a blind woman. No one would think a blind woman would be a serial killer. Also because the name is red john everyone's thinking is a man because the john part in the name. Finally her hair is red. So anyone who thinks its her i highly agree with you that she has a very high chance of being red john.