My third pick from the list of abhorrent Wiki charts mentioned by Jorge Camoes is the one from the page of Mauthausen-Gusen, originally a collection of villages of Mauthausen and Gusen in Upper Austria, which became one of the largest Nazi concentration camps by the summer of 1940 and the place of death of several hundred thousand inmates.
There are several reasons for finding this serving of pie unpalatable. Firstly because, it is a "Pie Chart". This same data could be more easily and effectively displayed using a column or a stacked bar chart. Secondly because, it is an exploded pie chart. I prefer an exploded pie chart where the exploded slice merits special attention from the rest. To otherwise create this type only succeeds in bringing a ragged look to an already poorly crafted chart. Third, and most importantly, the use of flags as legends and with it, the redundant use of data labels to state the name of the countries that is absolute chart junk! I'd either have the flags or the names as legends.
I've replaced the exploded pie-chart in favor of a 100% stacked-bar chart. Labeling the flags with the name of their nations didn't appeal to me much, hence the only labels in the chart are those showing the death percentage for every country.
This is, my version of the Mauthausen-Gusen chart.