There have been a lot of talks about the first series 10D because some of them seemed to have a front focus problem.
Although Canon never admitted it from series 7 the complaints suddenly stopped.
So check the serial, if it starts with a 6 or something below you might be in the danger zone, from 7 and up you should be ok.
Best thing is a quick test of course.
1. take a ruler or download the tool which I put on my website
2. put camera on a tripod with the aperture wide open
3. put ruler or tool in a 45 degree angle in front of the camera
4. select center AF
point and focus half way on the ruler or tool
5. take shot
6 examine the result at 100%
A good camera should show about as much sharpness in front as aft of your fixed focus point, in bad examples you will see blur in front and much more sharpness beyond the fixed focus point.