URLs a-gone gone

Google's 'list your URL' feature works well, amazingly well, all too well, when I tried it.

I would enter a URL, then complete the letter-recognition box that is intended to deter robo-listers.

The first couple of URLs worked.

The third one had a hard-to-read letter group and so I decided to hit the go-ahead button without attempting to fill out the form, in order to get an alternate, more readable letter-group. Instead, the page came up saying the URL had been submitted successfully.

I tried skipping the letter-recognition feature with another URL (about Joe McCarthy) and got the same result.

So, I'm wondering. Does that mean some monitor is deep-sixing pages I try to list, giving a false assurance of listing? I know that in the past many of my pages have been delisted from search engines. And some, which contain full-scale reports and not absurd odds and ends, seem never to have been listed at all.