Question tagging

A few days ago I saw something on a web page that startled me. The webmaster was apologising to his readers for having printed wrong information. (S)he had question-tagged a sentence that went something like, We've scarcely seen the last of them with haven't we. One reader had then pointed out the mistake. In fact the sentence should be question-tagged with have we?

We've scarcely seen them, have we?

I know, I know, it doesn't sound right, does it?
But remember that the word "scarcely" is negative, just like "never" or "hardly".

We've never seen them, have we?
Now that sounds fine, doesn't it?

The big question with me is: should we formalise and sterilise a language in this way? The first tag may be correct, but it sure as hell doen't sound right.

Take the question of prepositions, for example. We're supposed not to put them at the end of a sentence. But that often leads to stilted, non natural-sounding speech.

As Sir Winston Churchill supposedly said, that is nonsense up with which we should not put.