Nisen Bokeh
Of all the different types of bokeh that photographers use, this one is most hated by people who like to look at photographs (and even those who don't.) They might not know the technical term for this technique, but they don't like it. This style is known because it goes beyond just blurring the image and can have an effect on the photo, causing it to be distorted. This can really detract from the overall picture sometimes, which is why so many people don't like it. Also, it's used a lot by amateur photographers who can't pull off the more advanced bokeh techniques.
It doesn't really have anything at all to do with the skill of the photographer - it is entirely based on lens selection. This type of bokeh is what you get when using mirror reflex lenses.
You seem to imply that getting bokeh in your photos is a 'skill' that can be learned, and that you can even learn to have a specific type of bokeh.
It has more to do with the lens than anything else. Shooting with a large aperture will give you bokeh every time, assuming that there's something in the background to be out of focus.
The quality of the bokeh is a product of the lens design. There is no 'technique' that you can learn. The more aperture blades a lens has, the smoother the bokeh will be (if you had a lens with only 3 aperture blades, the bokeh would be triangular). Also, the blades on some lenses have straight edges, while others are curved - that halps to smooth it out too.
Mirrored reflex lenses will give you that ring shaped bokeh which most people find to be ugly.
EDIT
You can also make the bokeh any shape you want by making an aperture disc that you could tape to the front of your lens.
For example, you could take a piece of black posterboard, cut a heart shape from the center of it, tape that to your lens - now you will have heart shaped bokeh.
You could do the same for any other shape too.
