Poe's Law is one of the many eponymous laws of the internet.  It runs, roughly, that you can't tell the difference between religious crazies and people parodying religious crazies.  And vice versa.  That means that anything you find, for example, on LandoverBaptist.com you can find a real religious nutcase who believes it and says it. 

If Poe's Law is true, then I think it would be very difficult for charges of straw-manning to stick.  That is, no matter how crazy a view you can dream up about religion, you would likely be able to find someone who really holds that view. As a consequence, you'd never really be distorting the dialectical situation with the issue — there's always someone dumber and crazier than you'd anticipated. 

One thing to note, now, is that there's a difference between straw-manning and weak-manning.  That is, it's one thing to distort what some speaker or another may say and it's another thing to take the weakest and dumbest versions of your opposition and refute only them.  Straw-manning is the former, weak-manning is the latter.  The point is that if Poe's Law is true, it may be impossible to straw man, but the dialectical terrain is littered with weak men.  Your job is to sort them.

My worry is that without that distinction between accurate but selectively inappropriate representations of one's opposition (nutpicking one's versions of the opposition so they always are the dumb ones) and accurate and the best representations of one's opposition, we lose the thought that discourse is possible.  If you think that Poe is true about the religious (that they're all borderline nutcases or people who are simply enablers of nutcases), then there's not much of a chance at reasoned exchange with them.  Same goes for politics.  That's bad.

N.B.: Robert Talisse and I have a longer version of this thought over at 3QuarksDaily. I also have a longish essay on it up over at  my website on Academia.edu.