Well, I understand what you are getting at and I personally believe some are from the evil one.
I can give an example below.
However, if we discount dreams then we have to say that God, for some reason, stopped communicating one way he has all through scripture
When I was a child my pastor said he believes all men have had a dream from God revealing himself to them.
I believe that is true, the problem is that most people ignore dreams.
Now the track record here from some of these dreams is not good as far as dates are concerned.
But there are dreams that do line up with the word of God.
This is one way that God speaks to people to warn them ahead of time what the enemy has planned.
So it is true, some come from God, some come from ourselves, some come from the evil one.
So the devil tries to convince us not to do the will of God, where does that come from?
In our head, that is where the battle is.
Like Jesus rebuking Peter, "Get behind me Satan"
Guess where Peters thought to have Jesus not go thru the crucifixion came from.
I went to a Japanese book store recently and looked thru the few English Magazines
One was titled, "West Coast Witch"
It had a photo of a bunch of people that looked like Microsoft people on the front.
So I picked it up and glanced thru the pages, why I do not know.
I did not read anything, just looked at the pictures.
That night I had a horrible nightmare.
I woke up and said, where the heck did that come from?
Then I remembered glancing thru the magazine.
The devil is real folks.
We are exposed, usually willingly, to things we shouldn't
That is where some of this stuff comes from.