My husband and I have both been doing Yoga lately and since we usually don't do it together (he likes mornings and I detest them) we frequently use the same mat. Even if that wasn't the case, anything that you exercise on frequently surely needs a good cleaning now and then. Also some mats you can't tell one side from the other so who knows if your doing corpse pose on the side that was pressed against the floor last time. eeck.. Anyway, I found a bunch of sites that show you how to clean your mats without having to buy special cleaner which I've heard is hard to find at stores. Online you can get it for $10 - $20. 3 Healthy Chicks has instructions on how to deep clean your yoga mat , make a spray cleaner, a lavender spray, and a water/vinegar spray. So lots of options for any budget!! I also like this post on how to make a yoga mat cleaner spray with a how-to video!