2) They preach "another Jesus"
"Paul warns us of ministers who come presenting themselves as of Christ but instead present a different Gospel and a different Saviour. They may mention the name of Jesus Christ, but when you view the Gospel they present as a whole you find it deviating from what the Bible says. He warns us against believing such preachers quickly."
"For if he who comes preaches another Jesus, whom we have not preached, or if you receive another spirit, which you have not received, or another gospel, which you have not accepted, you might submit to it readily enough." (2 Corinthians 11:4)
3) Their preaching contradicts their lifestyle
"Many preachers today are able to speak with power, but the power is only limited to the pulpit – their lives show no evidence of God's redeeming and restoring power. Simply put, they don't practice what they preach; they don't walk the talk."