My way of thinking is, if you have to chase a potential customer then it will end up riddled with problems.
They'll either want it at the £45 complete house rate, or fail to tell you about the fact they're in the process of painting the walls (minus the dust sheet), or will cancell the job with 24 hours notice.
After 5 years I can now just about tell when the call is from another carpet cleaner trying to find out our prices.
Personally I only want customers who want me.