Even dan players cannot read ladders!
You will not believe me.
There are 8 (!) examples in my database where the cut at C6 was played.
All these mistakes were made by dan players!
There are 2 ladders here, and sometimes they read the longer one only.
Of course, black lost all 8 games - it's a 30 points worth mistake!
Here is an example from my own game on Dashn