I don’t like that I now have to think twice before printing PDFs — I find more and more they’re not actually designed to be printed — just viewed.
The reason: all the background colour. White text on a dark background looks nice on a produced brochure or report, or on a website, but not when I’m printing it at home to read in detail. It just hurts to think of all that ink being wasted — even if I print in grayscale.
Here’s a possible guideline: don’t design a PDF page that will be so wet with ink that it will warp as it comes off a consumer printer.