"A great frustration is when someone, usually a fiddler, starts up a set of tunes and by
just imparting a little info could have guitarists providing at least a basic accompaniment."

What information would you want imparted? I've tried saying "this is a set of reels in D"
and watched (mostly pop and country trained) guitarists just sit there like dumplings with
no idea what to do. Am I supposed to come with a chord chart written out in felt marker
and hold it up? Something short of that must work, surely?