How do I know if I'm looking at the corrected 6th edition of the APA Style Manual?
It is true that the original first run (first printing) of the 2009 6th edition of the Publication Manual of the American Psychological Association (APA Style Manual) had errors on as many as 80 pages!
APA has since corrected all the errors on these pages and removed the first run from circulation. In new reprints moving forward the date of 2009 is changed to the year the new reprint occurs. So, it is possible that the 2010 and newer dates can be used in citing the 6th edition of the APA Style Manual. Also, 6th edition dates beyond 2009 can be one indication that the APA Style Manual in-hand is indeed the corrected version. All 6th editions have the same ISBNs (for example, ISBN-10: 1433950618, ISBN-13: 978-1433805615). The most common citation for the 6th edition of the APA Style Manual is:
American Psychological Association. (2010). Publication manual of the American Psychological Association. Washington, DC: American Psychological Association.
In addition, reprints continuing after 2010 will have different dates such as 2011, 2012, 2013. To be accurate, it would be these dates, as reported inside the APA Style Manual that you have in-hand, that should be used in citations.
APA style does allow for edition information to be added to citations. So, it is certainly OK for a correct citation to look like this:
American Psychological Association. (2013). Publication manual of the American Psychological Association (6th ed.). Washington, DC: American Psychological Association.
If the copy in-hand of the APA Style Manual has a different date than 2010, use the date found in the copy in-hand.