I mentioned yesterday that I've paid a £319 poor-research tax because I changed hotels after only one night.
The original hotel, the Argyle Square Hotel just south of King's Cross, has mixed reviews. My experience traveling to London for 30 years told me that I could either avoid or ignore the difficulties some people had with the hotel. For example, Americans always complain about European room sizes and British plumbing. Always.
This time my experience failed me completely. This is the best photo I have of my room there:

By "best" I mean that it puts the room in the best light possible. That said, please direct your attention to both air conditioning units (the fan and the window) and imagine how effective they are cooling a 3rd-floor cell when it gets up to 27°C outside. Also imagine carrying a 16 kg suitcase up to the third floor on a staircase barely wider than the suitcase. Also imagine that the bed you see there—hard to tell, but it's just over a meter wide—has not a mattress but a decades-old box spring, so that you can feel each individual coil digging into your body as you try and fail to sleep.
Now imagine brushing your teeth and discovering that the plumbing isn't just quirky, it's producing really off-tasting water. And the shower, barely bigger than a coffin, is nowhere within reach of anyplace to put a towel or a bar of soap.
I have traveled to Europe for over 30 years, staying in youth hostels as a kid and "charming" old hotels as an adult, and I've never stayed in a room that bad.
Contrast that with the room I have now:

Almost the same price. And just the other side of King's X. And with a desk big enough for my Surface, books, charger, and bottle of water. And places to hang my clothes.
Once I fled the Argyle Square, I re-read the reviews on Trip Advisor (there are only 18!) with a more cynical eye. I can't be sure, of course, but the 5-star reviews seem remarkably similar. And the 1-star reviews seem a bit more genuine.
This hotel has over 4,000 reviews and most of them are positive. Not to mention, multiple electronic security measures, and actual plumbing that does not produce horrible effluent.
I am glad I moved.