If you are looking for an easy and free way to get new clients, check out www.hostgadget.com its a free service where people looking for clients submit their hosting needs, hosts then "bid" on their account.
Regarding HostVoice, I do want mention that as advertising can have very different results for different companies, we have plenty of satisfied clients (http://hostvoice.net/?testimonials), just as quite a few that didn't get great results from us.
The truth is that you can't quite judge the effectiveness of advertising from other people without trying it out for yourself.
If hostvoice is best for underpriced/oversold hosting, then so be it. There's a niche of customers who don't mind payin 1.50 for 5GB of space and 50GB transfer. But unfortunately, those customers will come and go like the wind until they figure out that you get what you pay for.
Well, I'm sure it was said before. Each business needs to find the right advertising for itself. If you find that its not working for you, just move on. There's plenty of more places to look.
That's not entirely accurate. We work with companies such as CIHost.com, LunarPages.com, and a wide range of others.
As for the leads - it all depends on the category you select. Shared Unix leads are more towards the lower-end spectrum, while eCommerce target businesses that are willing to pay more for quality service and support.