I agree with john doe!!
When The Holy Ghost speaks it is always in the positive.
Can we imagine The Spirit of the Lord telling Nephi in his first vision- "ummm Nephi, if you just take a gander over there to the left, you will see a virgin most fair...??"
No- he speaks a different language...He simply said "LOOK!!"
That's why we are counciled to speak in the positive as well. The Holy Ghost speaks that way.
If we don't know something for ourselves, and yet speak in the positive, it gives the Holy Ghost a chance to speak through us- giving(us), the speaker, a testimony of what we are speaking of.
Or, on another occasion we speak using our testimony, and the message is passed to someone listening, by the Power of The Holy Ghost(if they are a non-member)
It seems to me, or- "I believe", that The Holy Ghost wont bear witness to wishywashy words hahaha
I have been wrong often enough though...")