Does the sound of someone slurping down a thick soup or crunching on a chip make you want to die? Good news: you're not alone! Bad news: people are gross and will continue to make awful mouth noises.
The hatred of commonplace mouth noises like chewing or lip-smacking, and other sounds like the click of a pen, nail-clipping, or typing is a real condition called misophonia. Slate investigated misophonia, and found that, while there's still not a ton of research out there, there are plenty of people that suffer from it -- in fact, there are even Internet support groups dedicated to it.
A lab at UCSD was contacted by one misophonia support group, and, upon interviewing members, found that they all had strong reactions to "chewing, mouthy sounds." Doctoral student Miren Edelstein exposed both the misophonia sufferers and people without the condition to sounds like chewing, sniffing, and lip-smacking, and found that both groups had negative reactions to the noises -- the misophonia sufferers' reactions were just a bit stronger. So, basically, everyone thinks your mouth noises are disgusting.