On a pinto, sometimes you can do really pretty sharks teeth down their haunches. We used to do that on my advanced horse and it was lovely. All depends on how they're colored though - need a decent sized patch of the same color.
I also don't tend to like stencils unless there's a specific connection with the horse/rider, but love the look of freehand sharks' teeth on a shiny bay. I'd rather see time/effort put into basic grooming first (e.g., if your horse isn't already glossy, don't spend the time on quartermarks), but they can be a gorgeous final touch. I start by heavily fly-spraying the coat, then brushing it all in one direction. Then I take a short stiff brush and make a V on their hips, and then alternating diagonal sweeps on their haunches, so you get the sharks teeth pattern below. Finish with a vertical brush down the back to give a clean line.
What Katie said.
When blood is the beverage of choice, the sharpest fangs feed first.