We can use "focus" to draw attention to the subject we want to emphasize leaving other parts of the image out of focus — but how much out? You adjust aperture to get just the amount of out-of-focus quality you want.
Here at 100mm we focus on either the orange or on Nicole, and we try different apertures to fine-tune the fuzz. (This lens-distance combination can NOT focus on both Nicole and the orange at the same time.)
But there are degrees of "out-of-focus" that are just not enough and look like a mistake, such as panels 4 and 8. And, in this case, focusing on Nicole and letting the orange go out of focus just doesn't work well: in general if the "out-of-focus" object is large and close to the viewer, that can be annoying, just like putting something too close to a person's face for comfort.
Bottom Line: Use precise focus to draw attention to where you want it, but be aware of the subtle issues that come up.
100mm, ISO 800, TTL flash