The closed set
Unreadable is not one problem.
When a machine cannot read a page, the reason matters more than the verdict. A site that refuses crawlers made a decision. A site that renders only in JavaScript did not. A site with clean HTML and no markup is one afternoon away from being fixed. Those are different problems with different costs, so they are recorded separately.
This is the whole list. There is no ninth reason and no free-text judgement of your site anywhere in this product.
The page arrived, but its content is assembled by JavaScript. A crawler that does not run scripts sees an empty frame.
The page is readable as text but carries no structured data, so a machine has to guess what any of it means.
The site refused the request. This is a choice the site made.
The page was read, but the extraction did not clear the 0.7 trust gate, so it is not safe to rely on.
robots.txt asks machines not to read this path. Recorded as a data point, never circumvented.
The page was read successfully, but it is not a product page.
The page did not answer in time.
The result was inconclusive. We do not know, and we would rather say so.
To find out which of these applies to your own site, the check on the front page reads one page and returns one of exactly these eight answers.
See what a machine sees