I'm going to hate myself for doing this...
before you answer ask yourself if you believe in a God, whatever religion, and weather hi is all knowing, there for knows your thoughts as well and can read them. Most religions think of God as a being of good, and nothing he does is or can be evil. So if you think this, mind reading can't be evil, as for God, in whatever form you understand him, can read your mind. If you don't think there's a creator then knock yourself out answer either way.
And also I say the question is lacking, a gun isn't evil, it all depends on how its used, so would be the mind reading power.