Sometimes inadvertently the photos we take end up a little off kilter. We squat down or lean over in weird positions to get 'the perfect shot', but with our own vision at a weird angle, sometimes almost sideways, its difficult to ensure that the photo you are taking is level. While leveling it out may be your goal and produce a great photo leaving it a little off kilter can sometimes be more dramatic and just as nice.
Here is an example:
These are both good photos. Actually, its the same photo. I took the unlevel one with my camera and then cropped it so it was level. But, you can see from the unlevel photo that it looks a little more dramatic rather than just a static old fire truck sitting there. This technique works best when you are focusing on a particular subject rather than a large landscape. Also, usually the closer you are to a subject the more this technique is successful. Being far away, as in if I were 100 yards farther from this firetruck, would allow more visual cues into the photo that indicate a proper horizon and perspective.
While off-kilter photos don't always work it can be a break from dead level scenes and subjects. Try it out the next time you are out taking photos or doing a photo shoot!