Failure to alert or give an explanation

All bridge players agree about alerting and explaining upon being asked; but opinions are sometimes divided on what we have to alert. We hear and read incorrect assertions on the subject.

Should North-South alert?

Mr and Mrs Look-at-me were new to the club; the manager asked them their level and they replied, “Oh, we are in the first series [of the French ranking system]; we have been playing for fifty years but we are ranked poorly because we have never competed and play in a small club!”

Dealer South. Love all.

Over North’s transfer, Percaline deduced that her partner must be very short in hearts and, as he had not bid 2NT for the minors, it was quite likely that he had some spades. The non-vulnerable overcall seemed sensible to her, despite the suit being a bit anaemic.