Mmm, yes of course, it could be used for less than honorable purposes...but then, so could most mutations and abilities.
Charles raises an eyebrow but answers truthfully, "Not many and usually not without them being a telepath or similar as well. But I don't tend to pry willfully if someone does not want me to know something." Charles was one of the, if not THE most powerful telepath on the planet. "I have taught a few people how to put up some basic mental blocks and barriers."