We had house guests recently and on the day they were leaving they decided to leave earlier than originally planned.
A little bit of background info, we have fairly recently moved house, we have 2 toilets up stairs, 1 in the main bathroom and a seperate wc, when anyone comes to stay we mention not use the toilet in the main bathroom as it doesn't flush very well and sometimes won't flush at all. We also don't put any toilet paper in the room as no one uses it.
I clean the toilet that we don't use once a week just to keep it fresh, so 2 days after the guests left I went to clean the bathroom toilet only to be greeted with a massive shit in the bowl.
Now I don't care that some one forgot and used the wrong toilet, but to have a bowel movement and then not be able to flush it, you'd mention it right.
It seems incredibly rude to not mention it to your host, surely it was obvious I would find it, I understand that maybe they were embarrassed but again isn't obvious that I would happen across it.