How Avoid Poison Wods

In general, you don't really need to worry about this too much. About 8 to 12 years ago when Google was newer, smaller and less sophisticated, it was something to consider. They've become much more capable of determining things about a site and having a few "poison words" here or there won't cause you any trouble.

Now, if your "poison word" keyword density is high enough across your site and links pointing to your site use this poison word then this might cause you to be categorized incorrectly, such as being flagged as an adult site when you aren't one. This is something that would require a lot of deliberate action though.

One thing I have noticed is that sometimes sites that are involved in link selling for PageRank or other things Google doesn't like often have penalties applied to PR, ranking or both. This seems to be a manually applied penalty, not algorithmic. In other words, don't do stuff that pisses off the Google web spam team and shove it in their faces.

Also, there are "poison words" for Adsense that will trigger public service ads or even a human review by Google. For example, using "Katrina" on an Adsense site would trigger PSA's for hurricane relief, at least for a while.