We all know that Hungarian notation is bad. That has been debated a thousand times and closed upon. It has been proven that having type information as the variable name can lead to trouble. Some nice examples are here and here.
However, though most developers agree with the issues with type information in the variable name, there is some lack of clarity on the other aspects of variable naming. Like the m_ prefix. Many developers believe that it's ok to use m_ for non-public variables, especially because it can be easy to get confused between local and instance variables. Some even prefer just an underscore prefix.
The .NET Fx guidelines and MS internal coding guidelines clearly calls out against it and so does tools like FxCop and StyleCop. The reason is simple; it looks ugly and has other repercussions. For example if one uses m_ for instance variables, then he might want to call out static variables with s_ and global variables (yea C# is exempt) with g_. So one falls into the same trap while changing a static to an instance variable or vice-versa.
Moreover, these prefixes are simply not needed. The guidelines suggested way of using a this. prefix works much better, as you clearly use the this pointer indicating that the reference is to an instance variable. Topics like these turn into religious war during code-reviews or reviews of team wide coding guidelines. I personally believe that things like prefixes has no place in todays world of coding…