Ticks are horrible, and more prevalent when walking through areas frequented by stock (sheep/cows etc).
If you try and yank them out, the mouth-parts can stay in, causing subsequent infection. The tick-removing thingys are good in that you can sneak up on them - get really low down- then whoops!
We have found at the Blue Cross that anointing a tick with Frontline will kill it - maybe Frontline doesn't protect against ticks, but then again they can attach to all sorts of parts of your dog which you may not have sprayed.
If you have a short-haired dog, I have heard that covering the tick with Vaseline (or petroleum jelly) will smother it and cause it to drop off - but in the case of Cockers, not many parts are either short-haired or inaccessible by the tongue!
I can remember getting a tick of Popppy, my Lab, and pinning it onto an eraser so that the kids could see it - four days later, its legs were still 'rowing' - gross !!