I think we may be looking at different TripAdvisors...

MO Shanghai has 11 3-star reviews and 4 2-star reviews.

Pen HK has 19 3-star, 4 2-star and 9 1-star reviews.

FSHK has 44 3-star, 10 2-star and 11 1-star.



Take a look at the "Sort by traveler rating" on the left side above the top review, and you should be able to filter by only the negative reviews.

Ultimately, TA makes a lot of revenue from affiliate hotel bookings, so it's in their best interest to make you want to book whatever hotel you're looking at. I find that they often tend to sort reviews in a way that reflects that (with better reviews at the top) unless you manually filter the results.

That conflict of interest is just one reason (among many) that TA is flawed as a tool for choosing a hotel, though I do still find it useful as part of the research process (in particular, I find the photos helpful).

Here's a pretty good rundown of some of the reasons TA might remove a review at the hotel's request. I don't think it's as direct and unseemly as "pay for removal" (though I know these accusations are leveled regularly at every review site, and as many who have worked there can attest, Yelp has been known to engage in practices that, while not exactly what you're describing, many find disturbingly close).