When she screwed over Johnny Carson, it was the end for me too.
Was that after Johnny Carson played the practical joke where Joan thought she was being chewed out by Margaret Thatcher for making fun of the Royal Family?
IIRC she never forgave him for that. The actress who depicted Mrs. Thatcher had Joanie totally freaked out.
When she ‘screwed over Johnny Carson’?
http://www.people.com/people/archive/article/0,,20093711,00.html