It's not for me to promote John Kelly's stone cleaning course - however it might be something that some should consider.
About 9 years ago, I got fed up with just cleaning beige and off White carpets so as an additional alternative I went into stone cleaning.
It's a lot more satisfying than the average carpet cleaning. Did I have to start a whole new marketing campaign? - No. 90% of my existing clients had entrance halls, kitchens, utility rooms which were stone. A ready made market for me. Just a little bit of leg work & talking to banks and hotel chains and the commercial market opened up.
So unless you just deal with the lower end of the carpet cleaning industry, it's worth looking into this. I'm by no means anywhere the cheapest when it comes to carpet cleaning but I can assure you that the returns on stone floor cleaning/restoration pales those prices