Further to my previous post about the proper use of the gifts and the use of "thus says the Lord" as inserting inappropriate authority into a prophecy making it difficult for others to judge it.
I knew someone in my last Charismatic church who would, when he wanted to give a "word of knowledge" to someone, he would say, "I sense that..." and so on. This is a cunning way of saying, "The Lord has told me to say this to you." which is using an authority that we have no right to use. If the Lord is speaking directly, it is as though He is speaking Scripture. The reality is that there is no new Scripture further to what He has already said in the written Scriptures in the Old and New Testaments.
If a person is going to say, "This is what the Lord is saying", then they should quote the actually written Scripture, because that is the true Word of God. The person can go on to give his own exposition of the Scripture, but must say, "This is how I think this Scripture could be applied to you." What this means is that by quoting the Scripture, the true Word of God is given, but it is then made clear that the exposition is the speaker's own opinion on what he thinks is the application of the Scripture to the hearer.
If a person comes to be and says, "thus says the Lord", or "I sense that...", I immediately respond by saying, "I will wait until the Lord speaks to me directly to confirm what you sense that you are hearing from the Lord." In this way, I am protecting myself against a divination spirit imbedded in a prophetic word.