In            Existing Images 
Look            for points of light in the background. Perfect subjects for this are            distant points of light at night or sometimes light shining through            leaves or specular reflections in daylight. 
If            they all blend together nicely, that's nice bokeh. If they are perfect            little circles, then that's neutral bokeh. If they are all swimmy and            look little little rolled up condoms or donuts, then that's bad bokeh. 
