Personally, I have never heard of an ad being disapproved by Google AdWords for “text manipulation.”
I spotted a thread at the Google AdWords Help forums which has Laura, a Google AdWords review engineer, defining what “text manipulation” is.
The most recent case of this that we reported was with Regus AdWords sitelinks. Here is a picture from then, I currently do not see it anymore.
What if you are using them for real purposes, like for currencies or languages? Laura said you can ask for an exception:
Forum discussion at Google AdWords Help.
