Got this on a previous round. While our set has succeeded in protecting the carpet, I have to agree with Allegro100 and the others. The little "dimples" will hold a tiny amount of liquid, but because the letters dislodge easily, don't expect it to stop a large liquid mess.
The color selection seems quite random (I bought 3 sets), between yellow, red, green/teal, blue, orange and purple, though none of the pieces I received had the same color letter and background.
Also, keep in mind that this set does NOT come with border/edges, so if you intend to fully cover an area you'll need to find a way to fill the gapes at the edge or cut off the puzzle "fingers" on the outer pieces.