I think the "Save" button is one of those situations where it's an easy solution to what could be a very complex problem. In many instances, if you get rid of some of the "standard" ways of doing things, you're setting yourself up for a lot of extra work.

There is no extra work involved at all, just program as if the user always answered yes to the "Do you want to save" dialog. In other words if you use a messagebox to do this normally, wrap it in an if statement based on the user's preference to see it or not. Now all you need to do is be sure to initialized the variable used to "Yes".

The "dirty data" is just one example of it. In the situation where the save is automatic, you're going to have to check for a lot more things. Should it check for typos/spelling mistakes? In a perfect world, probably. What about incomplete records? Tag it for later fixing? Who's going to do the inevitable cleaning that will need to be done to clean out "dead" entries (those partial entries that people never got around to finishing or deleting)?

We are talking about the issue of saving the record here, not validations. Of course validations would still be required before the actual save takes place. Just like it would if the user clicked on a save button.