You'd still use a word like "toilet" and instantly (and forever) mark yourself as the filth you are.
...huh?
You'd have to carefully study the Brits to get that. It's a strict class hierarchy, still. Someone using the word "toilet" instead of, say, "loo", will instantly be recognise as lower class or lower middle class (worse).
I think you have it the other way around, "Loo" is the lower class one out of the two. Or even lower, use "Bog" or "Crapper".
That's what I thought, too, when I used "toilet" in place of "loo", and was told off by a certain witch who used to post here. According to her (and a sociologist who wrote about the English in a book I can't remember the title of, right now), "loo" is higher up.
The explanation seems to be that if you really are upper class, you don't have to care. Reverse logic but it makes sense.