Why does the Left call lies told by MSNBC 'mistakes' but mistakes made by Fox News are 'lies'?

Will the Left now start calling murderers 'life-shorteners'? Should thieves be called 'property-removers'? Should rapists be called 'sex-takers'? Why cant you people call a spade a spade? ooops I said spade, now I'll be called a racist.