Basically if you place a command block (with NBT data) next to powered redstone dust, on top of a redstone block or torch, or anything that should power it, it won't perform its command.

If you set up a situation like I have so in the attached file (by placing the torch down first, then the redstone and then the with the command block already having nbt data for its command before placing it in creative), the command block will not only not activate when placed but will also activate when removing the redstone dust or the redstone torch.

Sorry for my horrible description, but I didn't know how else to describe it.

Edit: The command used was "/say hi", but it seems as though it doesn't work for any command.