I've often thought of putting something like this on my leaflets and website but haven't because straight away you're saying that by having your carpets cleaned you're in a minority, not a good start to any sales pitch!
I've always stuck with " How Clean is Your Home", "Had You Had Your Carpets Cleaned Recently" or "How Clean is Your Home Environment", then list the reasons you should get them cleaned.
I would be more positive and say that more and more people are getting their carpets cleaned as the health benefits and lifespan of the carpet become apparent. That way you're target audience is thinking " I haven't had my carpets cleaned, how dirty am I" instead of "Well, no one else bothers, why should I"
Does that make sense?