I am not sure what upbringing you have or what etiquette norms are common where you live, but none of the topics above would be classified as non-polite in Europe, except maybe among very old and conservative people who would oppose to the dung beatles if their dung-related activities were dicussed in detail.
In most of European culture, especially perphaps in the South and the East, dinner is the family's main time for dicussions. Why do you think Italians, Bosnians or Hungarians eat all night?
In Sweden and other Northwest countries, I think 30-40 years ago you could have found some old farmer wives who think people should keep quiet while eating.
If you want to be polite, you should avoid talking about body fluids like vomit and excrements, detailed descriptions of accidents or diseases that include things that sensitive people may feel disgusted about such as blood, pus, intestines etc. So avoid descriptions of you ill childs diaharrea.
Does anyone else here routinely enjoy bizarre dinner discussions with their families, roomies, or.. pets?
Sure. Since much of my social life occurs in the form of dinners (everybody needs to eat even if they are very busy!), I almost enjoy excellent discussions with friends, colleagues, family or any combination of the three. We talk about the usual stuff - politics, arts, science, world events, our jobs, our interestest, our relationships, recent thoughs and ideas we have, experiences...could be anything from "look, I found this disgusting abscess on my leg, it has little green dots on, what do you think it can be?" to what should be done about the HIV-epidemia South of Sahara or "have you read this excellent book by Jelinek" or "I am considering killing my boss". It's usually nothing bizarre over my dinner conversation, although the other day when I was out with a friend, her 14-year old daughter called on her mobile and said
"Hi mom, I'm at daddy's, he's not at home and I'm going to take out his new motorbike. I just wanted to say that if I don't call back within 2 hours, I'm dead. Byebye mommy!"
