I do "OK" from yell.com. Without checking my stats, roughly 50/50 commercial/domestic (in terms of the number of calls). The rates for carpet cleaners have gone up in the last year or so, unfortunately, but I think a standard listing is only about 240+vat or something. If you do what I do and add on another area listing it costs about another 85. I spent about £400 last year and have made a profit from it, but it doesn't blow me away.
I think success on yell.com really depends the most on how many other firms are also using it. Not many others use it in my area, therefore my chances of calls and then conversions into jobs are greater.
Secondary to this, your description text or bullet points have to do the right job. You get six bullets... I try to make mine three service descriptions and three
benefits that the customer will get. Very tricky with limited characters.
They don't let you capitalise whole words to stand out, which is annoying

Web link is a waste of money IMO, the decision to call is made on nthe yell site, not by clicking through to your own.
Try a standard enhanced listing for a year and see how it goes, you only stand to lose a couple of hundred quid, which is one decent job!
One other factor you have to consider is the ability to SELL. You have to remember that if you shove a leaflet through a door, you are the only carpet cleaning company presented before the customer. A lot of folks would get you round to quote without shopping round any further. However, in any directory situation the customer is presented with multiple choice. They can and do ring more than one, so you have to GRAB them.
I shudder to think how many jobs we all lose because we can't sell properly. Most of use are tradesmen first and salesmen second.
I'll stop rambling now
