I've heard of some amazing things being "caught from a toilet seat", not so much with canoe seats of any kind. Sorry, but I've got to wonder if the problem didn't originate with a lack of personal hygiene.
But then again, maybe the person forgot the toilet paper and was unfortunate in his choice of shrubbery to wipe with. And the poor canoe seat was the passive victim of a false accusation.
Thinking back on it, before I became a confirmed solo paddler, I can remember telling a particularly lazy bow paddler: "You chap my a$$!!!" Wonder about any possible tripping companions and how they got along?
Sounds like the subject is ripe for a stalwart investigative reporter; Go for it Meopilite!
Rob