I know from personal experience because I had to scrape this off of my kitchen walls:
Ugh, it was so so bad. BUT, there is a lot of cool wallpaper out there! Currently my office looks like this, except the bottom red color was painted a different shade of brown after they took this picture. Yep, that means there are two shades of poop on the walls.
I do think the chair rail that goes around the whole room is pretty cool and I keep thinking it would be cool to put wallpaper on either the top or the bottom of the chair rail and then painting the other half a solid color. Here are some wallpaper options I've found in my internet perusing.
I'm looking for something whimsical and modern and, yes, possibly with dogs. I don't want to rush into anything too soon, but I have got to get the poop (figuratively speaking) off the walls before I go nuts! Do any of you have any experience with wallpaper in this day and age?