Since this works in Filezilla but not in WinSCP, I assume it is a bug:
I have a NAS (QNAP) with an FTP server on it. Since the NAS is used by OSX machines, users tend to put all different kinds of crap in their filenames (which I hate, but it is what it is...).
I'm using the .NET component to write my own sync script (to get various files from the FTP server and save them locally on a regular basis).
This works fine unless either the filename or a directory name has one or more trailing whitespaces. The problem is (it seems), that Session.ListDirectory(path) fails if the path ends in whitespaces. Also any returned RemoteFileInfo items seem to be stripped of trailing whitespaces, too, even though in FileZilla listings, they are clearly there.