Thanks for the tip! I'll remember that from now on.

I disagree. They're free to put ads on their printer friendly pages (which you'll notice The Economist has done), or add referer checking. I don't use printer friendly pages to avoid ads, I use them for their reading-friendly layout without enormous headers, footers, and sidebars taking up 3/4 of the page.

The reason we do this is that many of them have split the article or several "pages", which is super annoying to read.