I have been working as a CNA in the Med/Surg floor for a year. I interact with behavioral health and LTC patients frequently and I find the mix of patients interesting. I would say I enjoy it 95% of the time, although something may be wrong with me. On that note, I can not imagine being a CNA for 10 years. My experience in a clinic as a registered MA was vastly different. You shouldn't let this one experience change your mind. Try to find someone to shadow and see what you think.
By the way, there was one patient we had that was screaming for a while and I would just hum. It may not have helped her, but it made me feel so much better. They ended up letting us do ear plugs. Just trying humming all day until you find a better fit. lol.