I have been getting some good results recently from Espotting.. But you do have to be careful which key phrases you use. I.e Being highly specific is important - unless of course you have plenty of cash to burn!
Only setback with espot's is that you do need £99 to get yourself going.
The problem I am having with Espotting is I don't think it's bring in a return for the money spent.. I started fully tracking what someone is doing after they click from Espotting and most just load up the front page and you have to ask yourself.. why?
Also I track based on UV clicks and noticed that some cases the number of clicks from Espotting is higher than what my system says.. it's as if someone can click a listing and then click again and your charged twice.. of course that someone could have searched in the morning and again a night on the same day as I track a UV as being unique in the last 24 hours.