I always thought that was a huge part of it too. The teeth. I saw him live in the mid 90s. I can see why interacting with him might be difficult--the alcoholism was well known and yeah speaking he was hard to understand (on a live mic anyway I've never met the guy). But I love their music and don't find him hard to understand when singing. The studio cuts always sounded comprehensible to me.

Yes his alcoholism made it worse but I always understood him well enough. There were other singers of that era who clearly prioritized sound of word over meaning and were also hard to understand. Michael Stipe for example in R.E.M. I find it sad you know the guy personally and took the time to make this comment. And since plenty of us do understand his lyrics in songs, he really is not completely unintelligible when singing.

Punk music has never been about enunciating or singing properly. Someone like Christy Moore would not take the time to cover Fairytale of New York if it were not an awesome song.