I agree. I think demons can watch us and kind of tell what we are all about, but cannot read our minds. They can try to instill thoughts though, for us to grab a hold of, but if we grab a hold of the Holy Spirit and "cast down imaginations and every high thing that exaults itself against the knowledge of God" then the demon's little attempt is thwarted. In other words, think something else that is good, pure, holy and true. And if you really want to have the demons tremble, speak the word of God about the situation.