I for myself prefer to have nice temperament mares around me. I mean I do breeding because I love horses so why suffer and endure a difficult mare.
But I once had a mare that had bad character. She was beautiful, wonderfull mover, fast learner, love love to work and show, highly focused on her job and enjoyed it but didn't like to be around people otherwise. Work with her or leave her alone. THe only time that you could enjoy her was when she was in heat, Dr Jenkill and Mr(s) Hyde.
I would have liked to have a clone of her but with a nice attitude around people so I bred her to a stallion with that in mind.
This mare was manageable until she had her foal... then she became nasty and even dangerous when free but always very submissive when you caught her. I had to attach her in her stall if I wanted to be around the foal as she wouldn't allow me to touch him... However this foal could be qualified as my second most people oriented foal.
SO different from his dam, just a clone of his dad, conformation, color and character. First thing obvious is that he was friendly, just wanted to be with people. He would follow me everywhere, almost a nuisance. Loved to be cudle, brush, taken care of; she was a bit nervous, he was bomb proof; she was wary, he was confident; she liked to work, he was a bit lazy and so on.
I was planning to wean him early so he would be less imprint by his mom but despite all her attemp to be nasty, nothing could influence his profound nature and stayed equal to himself, just being a living teddy bear.
I didn't keep this mare but I wouldn't rule out a mare with a lot of quality because she has bad temper but would make sure to find the right stallion.