Great discussion, folks! I especially like littlerivermike's approach.
I guess I've encountered etiquette "problems" most frequently on Little River and Tremont.
On "streams-that-shall-not-be-named," and that includes many that are more than, say, 400 yards from where someone could park a car, I can't recall any real issues.
Of course, if a potential interloper starts to head your way, you could always use the "Hey, didja see that mess'a copperheads?" line
Best wishes to all.