Some of them get the levels wrong and will show you values below black level, which also causes blacks to be too milky. To test for this, run color bars through your camcorder and see if you can see all three PLUGE bars in the bottom right hand corner. (See monitor calibration instructions if you aren't familiar with them.) A monitor showing the signal properly will now show all 3 PLUGE bars. Looking at the LCD off-axis may show all 3 PLUGE bars clearer.
I do not believe there is any way to change the calibration on camcorder LCDs so I wouldn't try. Some cameras will let you change the signal... you don't want to do that. I would just test the camera and if it does not display the signal properly then I would keep that in mind and avoid using it for color decisions (though you probably shouldn't trust its color much anyways).
*I've seen this on my consumer Panasonic GS-70 and it appears to be the case on their prosumer HVX-200. I have not tested cameras extensively for this.