While ctrip and elong produce English versions of their sites which more-or-less censor out places that won't accept foreigners, Agoda and booking.com don't: their listings are the same regardless of language. Change the language of that booking.com listing to Simplified Chinese and it doesn't look so odd.

Turn up somewhere with a Chinese girlfriend, and they're likely to let you stay, even if they'd refuse you if you were by yourself..>
Sounds like a good solution! :-)
I didn't know Chinese people actually used booking.com
Also, the English translation is very good - it clearly has been properly translated by a decent English speaker.
The Chinese version proudly lets you know that receptionists speak Chinese! Other languages simply tell you that they speak "two languages". If you look at the site in a language other than English or Chinese, the all important warning that only Mainlanders can stay there still appears in English.
It's boilerplate booking.com uses on all listings with this restriction; they didn't do the translation specially for the 7 Days Inn Beijing West.
I mean the general description of the hotel:
"7Days Inn Beijing West Railway Station Lize Bridge offers simply decorated guestrooms. Free WiFi is available throughout the property."
... and so on.
Maybe that's the same description that's on every 7 Days Inn out there, including those that can accept foreigners. I'd presume, in that case, they also all claim to have English speaking staff, even if no one's ever actually checked.
Incidentally, I much prefer Home Inn - they maintain standards far better than 7 Days Inn.
And in several languages there is the brief notation "For Chinese citizens": "Citoyens Chinois Continentaux," "Para ciudadanos de China continental," "Cittadini della Cina Continentale," etc.
Home Inns is indeed fine, and if you can read Chinese their website normally tells you if a property does not accept foreigners.
I can't see a notation anywhere in local languages saying "For Chinese citizens". All it says is "Mainland Chinese citizens", and it does so in the title of the room, not in anything describing who can stay there.
The name of this room is the "Mainland Chinese citizens - special offer Twin Room".
It's not at all obvious - in English or in any other language - that what they're trying to say is that only Mainland citizens can stay there.
The only thing I hate worse in China than being called a 老外 is being called a 外宾. I've only ever heard (or seen) the term from hotels telling me that I can't stay there.
"I can't see a notation anywhere in local languages saying 'For Chinese citizens'. All it says is 'Mainland Chinese citizens.'"
"Para ciudadanos de China continental."
I was looking at French and Japanese, rather than Spanish. The equivalent of "Para" doesn't appear in either French or Japanese.
In fact, the Spanish version is even more confusing, since the "para" only appears in the description of some of the rooms, but not the others. You have a choice between the "For Mainland Chinese citizens room" and the "Mainland Chinese citizens room".