Had a quick goose around, and found a number of articles on poison keywords:
» Poison Keywords in Search Engine Optimisation
Turns out it was shonky SEO individuals using words like poison keywords to scare SEO noobs into investing with them.
I mean, it is a bit ridiculous. See how many forums are on the net. Be a shame if none of them rank for the word "forum".
I do understand however that for any given forum to rank for the word "forum" would be tricky. If say you are talking about "blogging forum" or "webmaster forum" or "bowling forum", you've got more chance, so I do kind of see that optimising for words like "forum" and "search engine" as a one off may not be beneficial.
I just don't like the use of the word poison.
(Apologies if any of the SEO gurus in this forum use poison keywords

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