Ethics of spreading false information

[peritonlogon]

This question is alluding to a very popular thread today, however, I'm asking a general question.

Is it ever ethical to spread false information?

For the purposes of this discussion I do not consider it spreading false information if you quote someone or reference an idea in the context of a refutation or an analogous circumstance, but do consider the statement spreading false information if it is merely a quote or the idea is simply stated.

Also, when there is an informative point to the quote, it is not spreading false information. For example,

Here is something pretty funny that Aristotle says in On Marvelous Things Heard "It is said that in the island of Gyaros the mice eat iron."

This question seems even more important in the electronic/internet age in light of these facts.
1) Most peer review journals articles are not available for free on the web. Which means most articles of value to in depth internet style discussion are unavailable for linkage.
2) Changing a person's Stereotypes/Beliefs has less to do with the validity/reason of the point/argument and more to do with the quantity of times the person is exposed to a differing Stereotype/Belief.
3) The repetition of points/arguments has more to do with how divicive it is rather than how true it is.