A dirty mind is a joy forever

I have heard Oscar Wilde quoted as saying, in part "...but a dirty mind is a joy forever." Is that a Wilde quote, and what iis the rest of it?

To me it just sounds quite unlike anything Wilde would have said; and the various Oxford dictionaries of quotations don't know it, which you would expect them to if it dated from Wilde's lifetime. On Googling, I have found it attributed to someone called "Randy Kunkee", of whom I know nothing. (VSD)

"A thing of beauty is a joy for ever" is the first line of John Keats' poem "Endymion" written in 1818.