I talked to a guy that was dark checking a lot of hands OOP. He said it gave him position by making the other guy act first, then he could decide what to do next. I politely nodded my head and hopefully waited til I turned by head to roll my eyes and scoff at him.
Many times the dark check is simply to confuse the PF bettor. If it is a heads up pot, I have taken a rather unconventional approach to the dark check. I bet dark.
If I am the PF raiser I am most likely going to C bet in position. If I am probably going to C bet anyway, betting dark transfers the confusion back to the OOP player. The dark bet may indicate a big pair or at least it could be interpreted as a big pair. If you do have a strong hand and/or smash the flop you may be more likely to get called or even raised after the dark bet. If you miss the flop the dark bet may invoke a fold from a better hand.
While this may not be the most optimal strategy it has worked for me on several occasions. And it seems to keep them from dark checking in the future.