The web application does not currently warn users about creating folders with invalid characters. For example, if you create a folder name that ends in a period [.] via the web, that folder never comes down to the Box client on a Windows machine. This is a limitation of windows.

However, other cloud providers WARN users before creating the folder in the first place and some even prevent the creation of the folder (Egnyte for instance).

A warning of "The folder you are creating contains an invalid character that may not be visible to users on Windows machines" or something to that effect goes a GREAT WAY to smoothing over the transition from a competing cloud provider to Box.