The danger of Koorong catalogues

I got another Koorong catalogue in the mail today and it is scary stuff. Firstly was "Daniel's Diet" 10-day detox plan, then NT Wright's commentary series (because it mixes so much good with the bad), and then Rob Bell's Nooma DVD's which are often just false teaching with a sugar coating. I remember that it was Jesus who warned us...."Watch out for false prophets. They come to you in sheep’s clothing, but inwardly they are ferocious wolves." Matthew 7:15