Maybe CS is a bad example since it's a really slow paced game. But take for example a really fast paced game like Quake3 or UT where you have to swing wildly around looking and aiming at players. When you're trying to compete with really good players in such a game every frame counts. 14% improvement in fps will make it slighly easier to lock on and follow fast moving players with crosshair since you will have slightly less jittering and a bit more responsive mouse which will equal to more smoothness in aiming. Most really good players make sure their games never run below 100 fps. And yes you can make your game run at higher fps than monitor can keep up with for a bit smoother controls (although you still won't see extra fps), but then your fps and refresh rate will be out of sink and you will have to put up with annoying tearing in your image. People used to turn vsync off back in old days because video cards were slow, now days there's no reason to do it. I'm too spoiled I guess, and I play games too much...
"Seriously, anyone who tells you that they are a better gamer at 85hz than they are at 75hz, or that it is a more enjoyable experience at 85hz than 75hz, is just plain idiotic."
I just ran some test and I could tell it was more jittery during turning at 75fps than at 85fps. Call me an idiot but it was more enjoyable for me at 85. If you're fairly new to shoot them up games, you may not agree, but as your reaction and hand eye coordination get better and better in quake3 and UT you will sense the difference easily.