Testing the Prophets

5 Thus saith the Lord concerning the prophets that make my people err,

that bite with their teeth, and cry, Peace;

and he that putteth not into their mouths,

they even prepare war against him.

6 Therefore night shall be unto you, that ye shall not have a vision;

and it shall be dark unto you, that ye shall not divine;

and the sun shall go down over the prophets,

and the day shall be dark over them.

7 Then shall the seers be ashamed, and the diviners confounded:

yea, they shall all cover their lips;

for there is no answer of God. (Micah 3:5-7)

This passage in the context of chapter 3 describes the abuse of power by leaders of God's people. The first and last verses of the chapter are very interesting too, but a few things about verses 5-7:
The false prophets have a tendency to tell people the kind of news they want to hear. They are not generally the ones with an un-likeable message of judgment or doom but with an appealing message of peace. But when this is the opposite of what God has actually said, the false prophets may as well be murdering God people considering the damage they are doing.
Interestingly, by being a false prophet one can lose the ability to see visions. This proves that false prophets can have real visions from God without necessarily being a true prophet.
If there arise among you a prophet... And the sign or the wonder come to pass, whereof he spake unto thee, saying, Let us go after other gods... Thou shalt not hearken unto the words of that prophet... for the Lord your God proveth you, to know whether ye love the Lord your God with all your heart and with all your soul... And that prophet, or that dreamer of dreams, shall be put to death; (Deut 13:1-5)
Even in the Torah we find a law dealing with false prophets that have fulfilled prophecies. So we should judge the teachings of a prophet on the Bible's teachings not by how many miracles he performs.