Second, I make absolutely sure my signature never appears in their logbook
meaning I will never pass them on a flight review.

Shouldn't we be telling these guys exactly what we think? I know of 2 pilots
that were killed in sailplanes where their instructor later said, "I knew it
was going to happen". Aren't we doing everyone a disservice by sighing them off
when we really don't think they are safe? I'm not talking about you Bill, But
someone is sighing these marginal people off every 2 years. If an instructor
were to tell them the truth, as he sees it, they might just get the message.
JJ Sinclair