I have noticed a pattern with both my single and divorced male friends. Most of them chew loudly with their mouths open while eating.
And, at first, I jumped to "oh, that's why they're single." But, it's obviously a result, not a symptom, right? Most of them eat most of their meals alone. And therefore, with no social norms or polite niceties to pay attention to, eat in the most efficient way possible.
It makes sense. And will make you feel sad the next time you're grossed out by it.