You know... I grew up with them, they are called 'Flachspüler' vs. the now common 'Tiefspüler'. From personal experience they were common up to 1990 or 2000. After this not so much anymore. Anyways, it had pros and cons, as everything. Pro: - no splashing up to your behind from stuff dropping down into your piss. - acessability for getting samples for medical 'shitworks' (not much of a factor, i had that maybe 5 times in my life?) Cons: Stinky, because 'open air', could be compensated by flushing early, multiple times.

Just for reasons of anti-stinkiness i prefer the 'modern' ones, and where i once placed a leaf of toilet paper into the bowl before using it to avoid too much cleaning, i now place a leaf of toilet paper into it to avoid 'upsplashing'.

Regarding cleaning, they usually were connected directly to high pressure piping, which roared liked the Niagara Falls trough it. Solutions with some tank up the ceiling with gravity assist were seen as inferior, and i may have seen them only a few times?

Never mind, back to topic:

[1] https://en.wikipedia.org/wiki/Bristol_stool_scale