Hello all,
Yes, you can opt-out. I can speak a bit of German, so had no problem, but you just need to ask for the boss "Chef". They will confirm that an opt-out exists. At DUS, it even says on the signs "Kontrolle durch den Körperscanner ist freiwillig", meaning "Screening through the body scanner is voluntary". In the EU, you can opt-out. Just ask for the boss, if they say you can't.
It's worth checking the main threads dedicated to this topic. Germany has had a 'crackdown' on security recently, and you can see my post detailing that on this page:
http://www.flyertalk.com/forum/25392498-post1332.html
the main thread can be found here:
http://www.flyertalk.com/forum/pract...canner-89.html
and a more frequently updated UK-specific one is:
http://www.flyertalk.com/forum/pract...2013-a-53.html