Aside from the dead pixels, I haven' heard of any indication of deterioration of the sensor.
Then I wonder why I haven't heard about the dead pixels in the video world? I guess the temperature of the sensors in the video cameras are kept more constant because of the continuous activation, whereas that of still cameras may be more fluctuated because the sensors are activated only periodically, especially the DSLR that doesn't use live views as default.
Anyway, I would stay away from a used camera of such high number of actuation, unless other conditions of the camera are acceptable and its price is "ridiculously" cheap.