I have limited experience with Mexican Red Heads (also called Green Cheeks).
A female was given to me about three years ago and is unbelievably sweet. The lady who gave her to me told me that she'd either love me or bite the snot out of me. She loves me

. With others, she's not very nice for the most part, although there are a couple people she likes. I don't know whether this is her personality as an individual or typical of Red Heads. She doesn't say much, but what she says is said with great heart and clarity. She spent part of her life next to where kids played video games. She picked up some truly awful noises, but doesn't use them too often.
A couple years ago, Joel rescued a male Red Head and I got him from Joel. He told me at the time that Lol-a was ornery -- and so he is. He now lives with friends in Georgia, where he continues to chew his way through all human flesh presented to him

As we don't know very much about his background, we can only assume that his behavior is probably a socializition issue.