I've got to totally disagree with this statement.
And I have to totally agree with Shaun that it is a silly thing to say. As DJs, one of the most important tools that we use is our hearing and it's something that we should really be looking after. It's a bit like a footballer not looking after his feet. Once your hearing is damaged it's gone. There are no second chances. And I'm sure my brother will testify to that.
Benny, it's actually quite refreshing to see people considering their hearing in our industry. To me, it's a crazy situation to consider anyone not doing that. Without our hearing we can't be DJs - it's as simple as that. Whilst the cheaper earplugs will do the job to some extent, I'd recommend investing the extra and getting a decent set of plugs. Something like this from Canford:
http://www.canford.co.uk/PROGUARD-ATTENUATING-EARPLUGS
I'm also wondering if those in-ear monitoring systems will do the job of attenuating the external noise levels at ear level. I've never tried them but that could be the perfect solution if they do.