After driving me mad for ages, I have found the reason behind the apparent madness that is Vista Folder Views, but first a history lesson:
In case you don't know; Vista (and other versions of Windows before it) allows you to switch between different views of your files and folders. Vista even has a nice button for it that cycles through the views. The default behaviour is to remember each folders view, which I always turn off (because it is annoying). In XP, that was all you had to do and "Details" (the king-of-views) would greet you wherever you went.
Not so in Vista - some folders kept their view. At first this seems like a nice thing: music, pictures and videos seemed immune to the change and kept their more suitable "Large Icon" view. However, normal folders would suddenly adopt strange views at a whim. Leave the folder all nicely organized, come back a few days later and *WHAM* large icons again. Most annoying! (I know there are worse things in the world, but these things magnify if you spend 12 hours a day in front of a PC, trust me!).
So what is the pattern? Smarter people than me have figured it out: Templates. There are 5 or so folder templates, and these are what your folder uses to decide what view it should have (assuming you don't allow them to remember individual folder overrides). So when you pick your view of choice and "Apply to Folders", you do not apply the view to *all* the folders, just to the folders of that template.
That is half the puzzle solved, but why should random folders start thinking they should use the "Music" folder template? Because Vista checks the folder contents (and perhaps even the subfolder contents), so if one picture appears in a folder, Vista thinks it is a picture folder and views it accordingly. If you want to know what template a folder is using, just right-click in some white space and select "Customize this folder...".
If you really want "Details" view throughout, you will have to apply it all the different templates. Even then it does seem to remember some local folder overrides, whether you tell it to or not - but it is still better than it was.