i have had the very same, a family house where the pan was blocked and they kept using it, until the last few must have had to stand over the pan to use it as it was piled up, the guy said "what did you want us to do , we needed to go" another one where the pan was blocked and they had simply sat on the edge of the bath and pooed into the bath, haha there was about 5-6 little piles where they had moved along a bit each time, my apprentice was physically sick at that one, they were both about 20 odd years ago and i still remember them, far too many others to distinguish one smell from the other