[walthamstow]

76250, or 93/100. Native English speaker from London. Some of the last 10 words were seriously obscure.

Are accoutrement and ziggurat really English words? Accoutrement is even pronounced as French!

[melasadra]

Weirdly enough, these words would be known to some non-native speakers as they show up every now and then in video games.

[stavros]

Depending on what you consider an "English" word, anywhere from 0% to 100% of words are English words. I've definitely seen accoutrement and ziggurat in English, and quite often.

[walthamstow]

Of course, the line is very blurry. I've used accoutrement(s) in English many times, but I've never considered myself to be speaking English when I use it. It's like joie de vivre or c'est la vie.

[stavros]

What about "rendezvous", or "etiquette", or "RSVP", cliche, nuance, etc? Do you consider those French or English?

As you say, the line is very very blurry.

[naishoya]

My favorite in the vicinity of etiquette and rendezvous is the "double entendre", very French sounding, but not French at all. That and something being not a person's "forte" which when correctly pronounced is just fort, but through confabulation with a musical term from Italian; forte: to play loudly, sounds more French to English speakers when mispronounced. C'est la vie.

Japanese loanwords really tickle my humour; バイト "Baito" : a casual, part-time, non-serious job. From the German "Arbeit" which is serious, macro-level employment or exertion.

[walthamstow]

Rendezvous and cliche yes. Nuance, etiquette, RSVP no. It's instinctive so I can't explain but maybe because rendezvous and cliche require using French pronounciation. On this I think you could find more differing opinions than there are possible answers.