I will tell you how you can know. (Dan. 2:1-9) "...tell thy servants the dream, and we will shew the interpretation. The king answered and said to the Chaldeans, The thing is gone from me: if ye will not make known unto me the dream, with the interpretation thereof, ye shall be cut in pieces...."
Stranger, you are making the argument here that an interpreter of dreams must also have a very powerful gift of word of knowledge or he is not a true interpreter of dreams. This is an unnecessary requirement you are placing upon interpreters, which would arbitrarily disqualify them from doing so. When Joseph interpreted for Pharaoh, Pharaoh TOLD Joseph the dream first. Joseph did not have to miraculously discern the dream without being told. Same goes for the servants who commended Joseph to Pharaoh to begin with:
"9 Then the chief cupbearer said to Pharaoh, “I remember my offenses today. 10 When Pharaoh was angry with his servants and put me and the chief baker in custody in the house of the captain of the guard, 11 we dreamed on the same night, he and I, each having a dream with its own interpretation. 12 A young Hebrew was there with us, a servant of the captain of the guard.
When we told him, he interpreted our dreams to us, giving an interpretation to each man according to his dream. 13 And as he interpreted to us, so it came about. I was restored to my office, and the baker was hanged.”
14 Then Pharaoh sent and called Joseph, and they quickly brought him out of the pit. And when he had shaved himself and changed his clothes, he came in before Pharaoh. 15 And Pharaoh said to Joseph, “I have had a dream, and there is no one who can interpret it. I have heard it said of you that when you hear a dream you can interpret it.” 16 Joseph answered Pharaoh, “It is not in me; God will give Pharaoh a favorable answer.”[a] 17
Then Pharaoh said to Joseph, “Behold, in my dream I was standing on the banks of the Nile. 18 Seven cows, plump and attractive, came up out of the Nile and fed in the reed grass. 19 Seven other cows came up after them, poor and very ugly and thin, such as I had never seen in all the land of Egypt. 20 And the thin, ugly cows ate up the first seven plump cows, 21 but when they had eaten them no one would have known that they had eaten them, for they were still as ugly as at the beginning. Then I awoke. 22 I also saw in my dream seven ears growing on one stalk, full and good. 23 Seven ears, withered, thin, and blighted by the east wind, sprouted after them, 24 and the thin ears swallowed up the seven good ears.
And I told it to the magicians, but there was no one who could explain it to me.” (Genesis 41:9-25)
By your criterion, Joseph would not have been a true interpreter of dreams. Or were you saying Joseph was inferior and somewhat deficient? This argument that suddenly all New Testament believers can interpret simply because they have received the outpouring of the Spirit is a fabrication based purely on theory. There's no support for it from scripture. It rests solely on a supposition. Every member on this thread who posted a dream was a Spirit-filled Christian, and while many had strong feelings about what their dreams meant, several had wondered without certainty for years, even decades, and others seemed to have little clue. What exactly are you telling them here simply because they posted dreams that they were either uncertain about or in reality really had no clue what they meant?