As I get farther along in my goal for better coding I've started to notice something. When before I've utilized the pre-processor region command I notice bad design. Before, I thought I was being tidy by at least visually grouping elements of a class into a certain section of the code. Very rarely though, does this make sense (the one place I can think of is still in the code behind for WebForm aspx pages [I typically have something like Properties, Events, Private Methods]).
If you finding yourself wanting to put region commands around a section of code, start to ask yourself, could this be it's own class? What it comes down to is the single responsibility principle and when you are adding region commands you aren't following it.