Usually it takes a whole presentation to prove that a ruler did a poor job.  One must look at battles lost or economic decline or large trends of their reign before making a judgement, but sometimes, just sometimes, the fact that a ruler was laughably bad is blindingly obvious, like if they only last 49 days.  This is the story of Liz Truss.

Azalea made a movie.  Go watch it: https://youtu.be/jbSveTQziTo