I've read about this sort of thing on the forums but it hasn't happened to me until today.

I received a book today that was exceptionally well wrapped.  The book is in excellent condition but it almost didn't remain that way because the sender taped the wrapper to the cover of the book. AAAARRRGGGHHH!!!  PLEASE, in the name of all that is good, do NOT tape the wrapper to the book!  This can cause tearing of the cover, rendering the book unpostable.  Fortunately, I discovered the tape before I gave the wrapper a good tug but the sender might not be so lucky the next time around.

I hope you PM'd the sender with a friendly reminder WHY the mailing guidelines state you should not tape anything directly to the book. They obviously did not read the instructions, so sometimes this is the only way to get the message across to the person who needs to hear it!

If I have a situation like that I always PM to say not to dowhatever - or what should be done.  I had one person send a book taped with masking tape!  I nicely wrote that the book arrived safe but the tape had been torn in a couple of spots so it would be best to use packing tape.  The person wrote back thanking me.   

I had a portion of the cover of A Tree Grows in Brooklin ripped off due to tape when I opened the package.  So sad -- the book was in great condition otherwise.

Hooboy, I've gotten a few of those myself. Ruined a couple of decent books that were on other people's wish lists. Of course, I couldn't swap them since the covers were torn to pieces. The only thing nearly as frown-inducing for me are the book mummies that I end up destroying because the sender didn't leave me a millimeter of air or nontaped area to open the sucker up. But that's a whole 'nother thread, isn't it...