- I think almost all the bookstores are not profitable, many of them closing down (especially the independent "second-floor" ones", ie not street-level stores). The book choices in mainstream bookstores are rubbish. (PageOne and Eslite slightly better.)
- 99% of the HK publishing houses are controlled by Chinese government by proxy. This imposes editorial censorship and determines which books will get promoted in the stores.
- If you publish or sell books that offend the CPC, you may be arrested in China with some false charges
- Generally speaking, most people in HK are not book lovers. If you visit Eslite (a Taiwanese chain), you'll see a large area of their store is devoted to lifestyle goods, not books.
Go to Taipei, go to Charing Cross in London, but don't go to HK for books.