It turns out that Fix Ubuntu has the solution:

#!/bin/bash



# Figure out the version of Ubuntu that you're running

V=`/usr/bin/lsb_release -rs`;



# The privacy problems started with 12.10, so earlier versions should do nothing

if [ $V < 12.10 ]; then

  echo "Good news! Your version of Ubuntu doesn't invade your privacy.";

else

  # Turn off "Remote Search", so search terms in Dash don't get sent to the internet

  gsettings set com.canonical.Unity.Lenses remote-content-search none;



  # If you're using earlier than 13.10, uninstall unity-lens-shopping

  if [ $V < 13.10 ]; then

    sudo apt-get remove -y unity-lens-shopping;



  # If you're using a later version, disable remote scopes

  else

    gsettings set com.canonical.Unity.Lenses disabled-scopes 

      "['more_suggestions-amazon.scope', 'more_suggestions-u1ms.scope',

      'more_suggestions-populartracks.scope', 'music-musicstore.scope',

      'more_suggestions-ebay.scope', 'more_suggestions-ubuntushop.scope',

      'more_suggestions-skimlinks.scope']";

  fi;



  # Block connections to Ubuntu's ad server, just in case

  if ! grep -q productsearch.ubuntu.com /etc/hosts; then

    echo -e "

127.0.0.1 productsearch.ubuntu.com" | sudo tee -a /etc/hosts >/dev/null;

  fi;



  echo "All done. Enjoy your privacy.";

fi

For 13.10, that's gsettings set com.canonical.Unity.Lenses disabled-scopes "['more_suggestions-amazon.scope', 'more_suggestions-u1ms.scope', 'more_suggestions-populartracks.scope', 'music-musicstore.scope', 'more_suggestions-ebay.scope', 'more_suggestions-ubuntushop.scope', 'more_suggestions-skimlinks.scope']"; and edit /etc/hosts to redirect requests for productsearch.ubuntu.com to 127.0.0.1 (localhost)