I don't get it. It also doesn't work if you're on a paginated page that doesn't contain those things.

Because then you know it's not on that page. With infinite scroll a negative response doesn't mean it's not on the page.

But then you can just go to page 2 and search again....with infinite scroll you have to scroll a set distance, wait, search again, repeat....how do you know you have scrolled far enough?

Easier to just click the Page 2 link and search again