Main message, many motives
"And many of the brethren in the Lord, waxing confident by my bonds, are much more bold to speak the word without fear. Some indeed preach Christ even of envy and strife; and some also of good will: The one preach Christ of contention, not sincerely, supposing to add affliction to my bonds: But the other of love, knowing that I am set for the defense of the gospel." (Philippians 1:13-17)
The Gospel is so dynamic that the even the motive of a preacher cannot take away from the potency of the message. Paul knew how to handle 'poor preachers.' He rejoiced despite other's attempt to 'add affliction' to his bonds. Things did not necessarily go his way, but he learned the great virtue of godly contentment. He focused on the subject of the message (which is Christ) and not necessarily on the messanger (be he 'good' or 'bad').