Good thread. The premise that feedback is unwise unless precleared or solicited is valid.
Unless feedback has been expressly requested, a good approach to playing a player you perceive as thirsting for knowledge is to offer them three choices before the play begins.
1) shot and situation specific feedback during the match
2) feedback only when the match has been completed
3) no feedback of any kind
Some have wisely suggested, however, that making feedback available to relatively new players that have shown an enthusiasm for developing proficiency at the table is important. They are absolutely right.
I always remember how Tony Robles, in the early 1990s, use to do this, at Corner Billiards in New York, NY. If he didn't know you but saw you a few times at the room, he often introduced himself and showed you a thing or two at no charge. Some will feel that this was Tony, an acclaimed instructor, soliciting business, but this was not the case. Tony was just being an ambassador for his sport and, of course, for his poolroom. Another player who conducted himself this way was straight pool guru Dan Barouty.
As some have implied, we're all ambassadors for pool.