Filth elder indeed! 

With the publication of his ninth book, “Mr. Know-It-All: The Tarnished Reputation of a Filth Elder,” Baltimore’s most reputable degenerate offers a sampling of all the things that make him such a civic treasure.

It’s outrageous and, in ways that only the man who unleashed “Pink Flamingos” on an unsuspecting public could get away with, sentimental. It peers into the future with eyes both delightful and decadent, and looks backward with a nostalgia for things many of us never knew we missed.

Beginning with chapters on each of his last seven movies (from 1981’s “Polyester,” the movie that gave the world Odorama, to 2004’s “A Dirty Shame,” with sex-crazed hordes taking over the Harford Road corridor), Waters moves on to ruminations on music, restaurants, traveling, fame, monkey art (as exemplified by the late great Betsy, a chimp at the Baltimore Zoo whose paintings earned her a cult following in the ’50s), death (he and his troupe of Dreamlanders have plots picked out at Prospect Hill Cemetery in Towson, near Divine) and — of course — sex (with a chapter we can’t discuss openly in a family newspaper).

So, just what happened at Camp John Waters?

It’s a delicious, deranged blend that may not be for everybody, and that’s just fine with the author. For the rest of us, however, tarnish has never looked so good.

We caught up with Waters over the phone from his New York apartment, the day after “Mr. Know-It-All” was released. Herewith is a condensed version of the conversation.

Q: Tell us about the pitch for this book.

A: I pitched it as, really in some ways, a continuation of all my past books. ‘Shock Value’ ended after I made ‘Polyester,’ so I said I was going to do stories about the movies I’d made since. And then essays about other things, like in ‘Crackpot.’ And then kind of a stunt, like taking acid, which in a way was like hitchhiking across the country (for his 2014 book ‘Carsick’).

Q: The chapter where you take LSD — did that start off as maybe an idea for a whole book?

A: No, it was always just going to be the one chapter. They said, ‘Be careful,’ and I said, ‘Be careful? If I was being careful, I wouldn’t take it.’

As it got nearer and nearer to the day, I was nervous. But I wanted to do it with Mink Stole. I think it’s the most sentimental chapter in my book, about friendship. I met Mink 50 years ago in Provincetown — that’s where we first met, so it seemed like a good way to celebrate that.

To be honest, all the other Dreamlanders said, ‘Are you crazy?’ And she said yes right away, because neither of us had ever had a problem with drugs in our lives. We took drugs when we were young, we never became drug addicts, nothing bad really happened. I never had a bad trip, and neither did she.

I always wondered, what would it be like again to do that again? As I said in the book, my mother always said, ‘Don’t tell young people to take drugs.’ I don’t think young people should take LSD. But old people? If they have pleasant memories of it and did it 50 years ago, I’m not so sure that one final nostalgic trip on acid is not clearing out some cobwebs.

This book is about hindsight and what I’ve learned throughout the years. I always figure that you have to dare yourself to continue to do new things. And it turned out to be a really great experience that I remember very fondly.

Q: There is a sort of melancholy to reading your books nowadays — every time you do a book, there’s more and more distance from your movies, and it seems less and less likely that there will be more.

A: To me, that’s not melancholy at all. I had a phone call today from an agent about a movie project of mine coming to life again. I take it all with a grain of salt, if it happens, it happens. I’ve never been busier than I am, my career has never been busier. I don’t know when I’d even make one.

I’ve made 17 movies; they all are still available. I just this weekend was recording all the commentary for the new ‘Polyester’ that Criterion’s putting out. So they’re all being rereleased, they’re not hard to find.

If I make another one, I do. But to me, the books do better — well, we’ll see, I don’t know what’s going to happen with this one — but the books probably do better than ‘A Dirty Shame,’ my last movie. That’s what happens.

Q: A good alternate title for the book could have been, ‘What the Hell Happened?” about becoming respectable and about becoming a Mr. Know-It-All. Do you, every once in a while, kind of scratch your head and go, ‘How did this happen?’

A: Yes, I do think sometimes, ‘How did this happen?’ But I always worked hard. My parents raised me to believe that anything is possible as long as you work hard and plan and work ahead.

I like my job. People say to me, ‘How can you have the energy to keep doing all this?’ And I say, How could I have the energy to not do it? That would seem like it would take me more energy to slow down.

You only get a certain amount of time to live, so I want to read every book, hear every new music. I want to know about the newest thing until the day I die.