A pastor cannot be a greedy man. He cannot live for riches. Money can be a great temptation and those that will be rich put themselves in a dangerous spiritual position (more to be said later in the book). One of the guideposts for a church to examine a man's character is whether or not he is eager for riches. This doesn't have anything to do with how much money a man actually has, but how much he wants it or wants to hang on to it. You can be poor as a church mouse but so greedy you'll hang on to a dollar bill until George Washington cries uncle.
The motive for desiring to be a pastor must be for the glory of God not for the money you could possibly make 1 Peter 5:1-2. A man has to be ready and able to make a stand despite the financial cost of doing so. If the pastor is greedy for money and possessions then he will administer his task with earthly riches in mind rather that what is right and what is true. Messages will be adjusted and blunted to avoid offending the big givers. Doctrines will be watered down to draw larger crowds. Compromises will be made in order to please those who control the purse. False doctrine will be preached in order to bring in more money. Look no further than the audacious riches of Rome to understand where the love of money will take you. Loraine Boettner wrote “The doctrine of purgatory has sometimes been referred to as ‘the gold mine of the priesthood’ since it is the source of such lucrative income. The Roman Church might well say, ‘By this craft we have our wealth.’”
That being said, the church should do all it can to support their pastor's ministry (Acts 6:4; 1 Corinthians 9:9;1 Timothy 5:18). The church doesn't pay the pastor so much as they support his ministry. He is not an employee, he is a servant of Christ unto the church. It is not the churches duty to ensure the pastor stays humble, God takes care of that.