They do work well, although they are ugly.
But they do fade, sometimes completely, and I've tried everything to keep them going through a single season - ballpoint pen, number 2 pencil, Sharpies, china marking pencil, and so on.
Two hints that work for me:
1. You have a lot of blind to work with from one set, so don't be stingy. Cut them longish (one end flat, one pointy to make digging it in easy) and write the name and variety twice. Bury one labeled end in the soil and the sun and weather won't fade it.
When you need to determine what pepper you're harvesting in October, you won't have to guess, just pull out the label and put it in the same bag as your harvested produce.
2. Since sun fades your tags, be wise when you set them - face the labelled side to the north - the shady side. Works for me.
I wish I was a better photographer, my blog would be much more fun. But who takes pictures of faded plant tags made out of old Venetian blinds?