Old towels are a dog owner's best friend.
When it's muddy out, I lay a couple in front of the back door to catch the worst of it. When I see tracks, I stand on one of the towels and shuffle my way over the tracks and then toss it in the wash.
Is the floor perfectly clean? Heck no. But it's clean enough until the next set of tracks get laid down. I have probably 20 "dog towels" I keep in the laundry room.