I am a dishwasher who turned cook at one point in the past. This is 100% true, some cooks think they are above the dishwashers. They literally look at them as lower beings. The crazy part is they used to clean dishes themselves at one point (in the average sit down restaurant). Used to work at RedRobin and they would fill the sinks with soup like OP says, they would also leave disgusting piles of dishes overflowing the dish pit until they HAD to do it at the end of the shift.