My dad was in denial about his hearing loss for about 20 years, most of it after I had left home for college. The burden of living with a hard-of-hearing family member fell disproportionately on my mom, who was left at home alone with him. She grew increasingly bitter about it over the years–not because of his disability but his refusal to do anything about it. They would get into screaming arguments about it. His stubborn denial took a huge toll on their marriage. Years and years later, he finally got hearing aids, but by then he couldn't adjust to them and seldom wore them.
So if you are looking for symptoms of hearing loss, don't just consider the person's frequent mistakes about what is going on around them, and their missing of social cues, but check out the state of their relationships with family and friends (probably dangerously frayed), and their growing social isolation. In my family, hearing loss was a hideous disability.