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.
Text manipulation is what we call it when people use text from multiple languages or Unicode blocks to try to game the system and sneak ads past our automated filters. A trivial example is someone using the Cyrillic letter that looks like a 'P' in order to advertise iPod without getting caught by trademark filters.
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:
If you think those characters are legitimate in your ad and you weren't trying to game the system or just make the ad look distinctive by using weird looking ones, feel free to ask AdWords support to re-review the ad. The link below has information on how to contact them -- make sure you've logged into your account before clicking it. You might see a phone number (I can't remember if we have phone support in Asia or Australia) and there will be a link to a contact form as well.
Forum discussion at Google AdWords Help.