The first place to start with how to make your couch smell good? Grab a box of unopened baking soda and start sprinkling! Don't dump it all out on one spot, but gently snow the baking soda all over and allow it to sit. Pull out the cushions and give the inside of the couch love, too.
Walk away for an hour, and let anyone in your house know not to disturb the couch during this time. Then vacuum it up! If it's improved but the smell isn't fully gone, sprinkle, wait, vacuum, and repeat.
Baking soda is especially great at countering those mystery pet odors.
Quick Tip
Make sure there are no hidden puddles or wet spots on the couch before busting out the baking soda. You don't want to accidentally make a paste or any fizzy science experiments.