People are so ignorant

People are so ignorant Hey guys I gotta get this off my chest. I worked a customer facing job for five years and sometimes when I would stutter, the person I was talking too would change. Their whole demeanor and tone would shift and they would start talking to me like I'm stupid. I'm not stupid. The sympathy on their face and the way they felt the need to talk to me like I'm a special needs toddler was infuriating. Has anyone else noticed this and how do you deal?