The problem with carpet cleaning customers is that they are very fickle. Even if you do a fantastic job for them, the next time they want their carpet cleaned they still ring around for prices and often go with the lower price, believing that they are getting the same thing this time, only cheaper. If you really did do a fantastic job then they will be disappointed with the outcome of the current job and think it isn't as good as last time and come back to you because they have now learned that you do the better job, albeit for slightly more. That is when they become YOUR customer.
They also don't tell you that they became disappointed when the carpet appeared to become dirty again only a few days / weeks after the clean, what they do do is decide there and then not to use you again and will go elsewhere next time around.
Using an obscure cleaning method like VLM where your chances of getting the carpet thoroughly clean are so much less, that then increases the chances of the customer becoming disappointed only days after and kills any chance of you getting a repeat job which is the life blood of any carpet cleaning business.
Your initial marketing gets you through the door, but it is the quality of what you do when you're in their that decides the future of your business. Every job is an advert and using the least effective cleaning system that leaves a residue and therefore cannot be done repeatedly is going to reduce your chances of building a successful business that is based on repeat and referral work and that in the end is bad marketing. I'm not saying you can't build a business on that basis, but it's going to be really tough going with a perpetual chase for new customers.
It's a bold decision to go down that route and I think that is all people were trying to point out to David.
The art of building a successful carpet cleaning business is to put your customer in a position where they can't get what you do anywhere else.
Simon