After all these years ....
We had an incident where an editor created a spot with a fade up from black. AMAZING! 
But what was interesting is that QC noted that the frame 1 of the spot was entirely black. Normally they would see some small video level present on the first frame. First field if it was interlace. This started several of us trying to figure out what was happening as it was reproducable. The answer is odd.
If the fade from black has filler before the first scene of video which is fading up, then frame 1 of the fade wil be black.
If the fade from black has real media of black before the first scene of video which is fading up, then frame 1 of the fade wil be the small bit of video level we normally see.
What is even more interesting is that this holds true whether you use a Dissolve transistion or a Fade From Color transisiton.
It seems that filler is acting different than real media in this case.
Something to keep in mind.
Jef