Very effective! I wonder if Google will forbid such tricks once they notice.

I am also having these kind of weird characters in my web page titles and descriptions for ages, using a single HTML file to pick one of the many UTF-8 letters. You can download this handy file from here:

http://www.wideweb.hu/download/

I don't see it.

Wow,
I just tried it in adwords and it works!
Thanks József Jároli

Anyone know if this is against the TOS? Can the use of these characters be a problem?

I got an email from them... they're are not allowing it.
They removed my ad.

Yes, Just a warning, they consider these characters improper grammar and will shut down your ads if you use them.