Didn't look that bad to me. I've had machines turn up on site with the seat and leavers that dirty. Its all dry mud, would only take a few to give it a quick wipe out whilst its warming up if it worried you, but really if you are an operator for hire surely you have seen dirty machines before. I wouldn't leave my machines like that, but he is only there for a couple of days covering for someone. If it rains again and he has to wade out to the machine through the s**t, what does he normally do, take his boots off outside and operate in slippers?