Yeah, that might undermine attempts to naively search for a list of predetermined words.
What does undermint mean?
90% of the Mint/Mine jokes are like this: Very short posts, coming directly after and/or quoting a post that contains one of the words, having moderate respect. There are two or three subtypes of this, for example such as the one we see, where the quoter swaps which word is used. Or, also popular, such where "mine" is used as the regular word for "my stuff" in the original post, and then the "funny" post writes it capitalized and mentiones Treasures, Engines or a Dominion edition.
Even if I just removed all short posts which mention either card and come right after another post which mentions one of them, as long as I exclude, say, the rules question, puzzle and all Base- or Prosperity-specific threads, I feel there's a low chance of false positives. Nobody talks about Mine or Mint. Going into a case destinction to look for one of the ~3 types of these jokes should probably allow to also apply them to forums where a mention of Mine or Mint is not incredibly unlikely.
Point in case: My post is too long to be a punchline.