Using private variables in cached .net classes is a recipe for strange and often hard to debug problems.
See for instance: http://code-smart.org.uk/information/beware-asp-net-mvc-actionfilterattributes-are-cached-between-requests/
This can leed to session mixups/swapping! Usually these problems are blamed on not setting the output cache correctly.
Can (should?) Resharper detect these problems? Or is there another way?