John,
I have used brushed in blinds, and not so brushed in blinds and was successful. As has been said, covering the windows with mesh or at least breaking the "Big Black Hole" effect of the windows is important.
Here in Oklahoma, on state land, we can not cut any foliage either. In a fairly short time though, I have always been able to find broken branches or deadfall brush I can use. I have a few different brands of blinds. It seems to me that the more domed shaped ones are a little less likely to spook deer than the really square ones. "No straight edges in nature" comes to mind.
I also hunt in big timber bottomlands and use big slabs of bark more often than limbs or brush to help my blind blend in.
Good Luck.
OkKeith