What's really important is to get the soap and whatever the stain was out of the fabric. If there is any soap left in the fabric, it will tend to collect dirt over time. Extraction of the residue by suction is the key. You could buy a small upholstery machine (like the rug doctor portable that I have) or use a wet pickup shop vacuum and nozzle. You need to get a fairly large amount of water onto the fabric and quickly vacuum it up before it soaks into the seat. Upholstery machines spray liquid just in front of the vacuum nozzle so pickup is almost instant. I use the cleaning soap in a spray bottle and brush it in. After setting for a couple of minutes, I use the machine to spray the water and provide suction to pull the soap out--never putting soap solution in the machine. The nozzle is clear plastic so you can see what is coming out of the fabric. I do several passes until the water coming out has no visible foam from the soap. Then I place a fan so it blows on the area just cleaned until it dries. Having a dog and fabric seats, it works for me--time and time again!