I've used just about every carpet shampoo out there over the years. Because of this forum, I tried Folex and like it very much for my spot cleaning (and yes, it's available in gallon size). Recently, (also because of this forum) I've used several Zep products. I'm VERY impressed with their odor eliminator and their carpet shampoo. Here it's only $1.98 for a 32oz bottle of the odor eliminator vs. $3.99 and up for Lysol, Febreze, etc and IMO, the smell is better and lasts much longer. Now for the carpet shampoo, I think there are 3 types. I bought the red gallon..high traffic I think. Foams up a little, but not horrible. I must say it got my carpets (in my home) much brighter than any other carpet shampoo I've used. Once it FINALLY stops raining here, I can't wait to shampoo the carpets in my truck! I'm now a huge fan of Zep products!!!