Copy-paste a post of yours (preferably a decent paragraph) to find out how "polite" it is. Ideally, try to use examples of you being formal, because there's no point in being polite if you're just going to shitpost.
Disclaimer: no clue how scientific this algorithm is meant to be. Treat this as for fun only.
Mine:
I tried out a few of my paragraphs. Most of them were neutral, a few impolite.
I guess posts made in debates are bad for this, because they naturally contain a lot of negative language regardless of formality. I think the most ideal kind of post would be a paragraph introducing yourself, but I don't have any of those handy.