Yes, that is true.   However, I think I read somewhere that Google checks for that and will actually penalize your ranking for using that method.  I don't know if that is true, however, it would be possible for a search engine to determine the background color and the text color to see if the text is visible. 

I think we experimented with it briefly but we dropped it.  If you ever do a CONTROL "A" to "select all" on a web page, all of the text turns while with a blue background (or some other viewable combination) and you will be able to see if anyone is hiding text on a Web page.  Try it here.

HERE IS  SOME HIDDEN TEXT!

Best,
Robert A. Franco
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