Usually, a blurry shot is not considered a good thing. Lately though, I've come to see the beauty of how deliberate blur can be used to create interesting and artistic shots. Desirable blur in photography is called "bokeh." Good bokeh is an out of focus area in an image that is aesthetically pleasing. Out of focus lights are a common way to capture bokeh in an image. The lights may be a background element or the subject of the image. The latter can be a really nice abstract work of art.
I decided to experiment with bokeh lights on a recent photowalk in downtown Austin with some of my Flickr friends. These images are of the same scene, the 1st St. bridge over Lady Bird Lake. Both are pleasing to the eye (in my humble, yet biased opinion) for very different reasons. One captures the detail of the structures, subtly complemented by light reflected in the water. The other image is an abstract display of symmetrical light and color. To get the bokeh shot, I simply defocused my lens and captured an exposure as long as I could without blowing the highlights.
The shape of the defocused light points will depend on your aperture. A wide aperture will yield round shapes. This bokeh shot was taken wide open on my 30mm prime at f1.4. A narrow aperture will be more like a hexagon, depending on the number of blades to the aperture.
So, blurry photos aren't always a bad thing. I had a great time experimenting with this artistic photography style. Give it a try!