What is this seat cover you speak of?[I]

In my opinion, yes.

I used to put te seat down then, my wife used the toilet in the night and forgot, needless to say I heard all about it.

Yes, it's best left down before flushing to lower the amount of spray into the room

That seems a little knit picky to me unless they person complaining is a germaphobe. In that case I would try to comply. In my house I mostly keep it closed but not always. I also live alone and do what I want.

It doesn't bother me if they leave the cover up, but I prefer it to be down.

I took the seat cover right off my toilet and now use the cover as a cutting board in my kitchen. It works great because it's hinged against my backsplash beside my stove and stows up and out of the way when not in use.

It is not a matter of manners but more of a lifestyle, once you are accustomed to putting the toilet seat and it's cover down every time you use the loo, it becomes normal that you do it subconsciously.

Freedom