Often these verses are based on, or direct references to books with drugish backround:
K9 – William S Burroughs – "Nova Express"
SNAFU – Robert Shea and Robert A. Wilson – "Illuminatus"
Phanerotyme – Aldous Huxley (in a aconversation)
and many more
I think a lot of Motorpsycho's lyrics are inspired by novels, books and fiction. Also in non drug related context.
Same thing with music, just to name Grateful Dead, Spritualized and others…
I think its interesting, but it doesnt matter to me if they did drugs themselves. At all.