glitterball - 6:49 am on Apr 14, 2013 (gmt 0)
@ garyr_h & azlinda
I've been thinking along the same lines - I offer some of my sites in 2 and 3 languages and up to yesterday, I was using the same ad units for multiple languages.
Yesterday, I created entirely new ad units across the board with distinct units for each language. I'll let you know if it makes any difference.