Thanks Roger & Clinton

Clinton - I almost always try to get an in-home quote arranged. I have got pretty good at filtering out the time-wasters, usually it's their first line that gives you the best idea. The price shoppers ask for a price, simple as - I don't waste my time and simply give them a nice high estimate but emphasise that I can't fix a price until I've seen the job.
Those more quality-oriented ask for a quote or say "I'm interested in having XXXXX cleaned...", to which I'll respond by asking them when they'd like me to pop round and have a look - most are happy to oblige and that's where I do the selling. Quality customers generally want to know what you're like before they book you in.
I have had a few surprises from phone quotes actually, some of them do phone back later to book in, but not many.