Does a distinctiveness score demonstrate anything about a produced page
The question arrives every time a spam update drops, and it arrives in the same shape: someone has a batch of generated pages, a checker that reports them as highly distinct from one another, and a feeling that the number is not answering the question they really have. They are correct to be doubtful, and the explanation is easier to demonstrate than to argue about, because both halves of it can be checked on the same set of pages in roughly a second.
I produce location pages for one service, one page per town, from a skeleton with a lot of synonym slots. My checker says the pages hardly overlap, which everyone tells me is what you want. But the search engine’s own policy lists synonymising as an example of the thing it acts against, so which one am I supposed to believe, my score or their page?
Both, since they are not measuring the same thing. The policy language is about what a batch of pages is for and how little it adds for the reader; the method is explicitly not the offence, and the same sentence says so whether a individual or a machine did the writing. A similarity score, meanwhile, measures variation density over short stretches of words. A pool can push that score as far as it goes and still express one thing in many costumes, which is the phenomenon the policy example describes rather than the reverse of it. The first thing to determine is not how different the pages look but where their differences originated.
There is a test that reveals where the differences came from, and it requires one pass. Replace every value that originated from data, the town name included, with a placeholder, and check the pool again. If what remains is many pages that are still unique, the template produced them and the reader gets one page every time. If what remains collapses to a single page repeated, the data was holding the difference, and the pages are worth as much as the data behind them is. That second part the test cannot resolve for you, and no measurement can.
Why the score moves the wrong way when the documents carry data
Construct the same pool twice. Once with synonyms and nothing else moving, and once with no synonyms at all but a number of real values tied per page, the sort of thing a listing would hold. The synonymised pool rates as barely overlapping. The pool bearing values scores worse, because facts repeat across pages in the same sentence frames and short word runs survive. By the score, the pages built to say something particular look like the questionable ones, and the pages telling every town the same thing in different adjectives look clean. That inversion is the whole answer to the original question: the score cannot distinguish a pool that says something from one that merely appears varied, so a good number is not evidence of anything the policy weighs and a poor one is not an charge. It gauges the surface, which is exactly the part a synonymiser is built to move.
The report, with both pools measured and the file that replicates them: scaled content abuse
Run the deletion pass before the publication decision rather than after, because it answers a question the dashboard never will: what does a reader find on the second page that they did not receive on the first. If the answer is a different arrangement of the same sentence, more variation will not fix it, and the number that claims otherwise is measuring the wrong surface.