The short and direct answer is an emphatic 'No'.
There are some 'general' items like a VA description/definition [check Wikipedia for a good one] and/or a Code of Ethics that are offered on some sites for copy/paste with attribution but otherwise you should always assume that content on anyone's website is their own creation and as such, copyrighted. Sadly, though, that is not always the case - re: conversations here:
What can you do when someone steals your original website content and images?
and here:
Plagarizing website content is a big no-no
Recently a site I wrote for another VA was stolen completely, word for word - the original VA paid a good deal of money for professional, original content only to find another VA who didn't feel like doing the work herself had 'borrowed' ALL of that content. As you might imagine, neither of us was pleased.
As a business owner it's more professional, and more reflective of yourself/personality/philosophies, etc. to write your own content rather than borrow someone else's.