The pics posted above by Eric and Sarah are examples of lack of D.O.F.
That can be both a good thing as well as bad.When the WHOLE subject is in perfect focus and the background is blurred,then that would be a good example of lack of D.O.F. and how it can be used to make the subject stand out.
Sarah,your last(clown pic)shot is an example of good D.O.F. The whole picture is in focus,unlike the examples I posted above.