Now... if there is a medical issue that I don't know about there ears, (and I'm not talking about ear infections!!) then there maybe a reason. But if it's just to make them look "mean" or because "They won't look like a dobe" then forget it!!!!
as far as i know there is no medical reason to crop ears (JMHO it looks awful) and it is just to make the dog "look" mean some people. *cheers* we dont crop ears in austrralia *legally anyway*