Your observation is not only correct, but is consciously and deliberately driven by Amazon's (and others) algorithms, which pretty much never show you what you're searching for, but rather repeatedly re-list similar paid-for content, for page after page. Google and other search engines do the same. They all seem to almost completely override Boolean search terms now. You're not seeing what you want to see, you're seeing what they want you to see. Sounds paranoic tinfoil-hattery, but for them it's great business - stack another $trillion in the vaults &c...