I agree that a lot of what is called prophecy... isn't. I have seen lots of hype, sensationalism, cult of personality and other c**p being passed off as prophecy, and it disappoints me, because I firmly believe that the gifts are as much for today as for the early Church. I also think that this gift/ministry is maligned so much is because the real thing is powerful, and the enemy knows it, so he works hard to discredit it, often using the pride of man to do so.
I have personally witnessed and experienced operation of the gifts (not all... I haven't seen the dead raised... yet) including prophecy, in the right sense, so I know the real thing exists, and I have some experience to determine what isn't real. Any exaltation of the person giving the word indicates something is off-kilter. Agabus didn't exalt himself; he was recognized for the gifting from the Holy Spirit.
The biggest problem I see is that prophecies are not tested. The gibberish which PostHuman compares (fairly!) to horoscopes are far too generalized to be properly tested. Every year sees new "words" that the Lord is going to do something new, something great, and like the horoscopes, these things cannot be nailed down to be examined. The gifts are intended to work together, so elders, shepherds and deacons are to examine and consider prophetic contributions, and weigh them against the Word and against actual fulfillment.
The other problem I see, linked to the first, is that in every other gift, people are encouraged to grow in it. With prophecy, people try to apply Old Testament tests to New Testament gifts as an all-or-nothing. I think we need to encourage potential prophets to submit what they hear to testing, that they may be refined and edified in how they hear the Lord, and learn not to embellish or aggrandize what they do hear. Where the gift is real, it will be proven real, and will be accompanied by good fruit.