Why do some nose jobs look done while others look natural? How can you tell the difference between them?

... because you don't know whether the person has *had* a nose job. If you see a nose that look unnatural -- something about the contour screams "operated," then of course you know that the person has had surgery.But if you see a nose that looks nice and natural, was it a very good nose job, or was the person born with that nose? Hopefully, after your surgery, people won't know whether you've had surgery, because your nose will look so natural.See the "Web reference" link, below my response, for advice on making sure that you get a good, complete consultation, and you can make a good evaluation of whether the doctor is good enough to operate on you.

The bottom line of choosing a natural result is one that looks good to you and no one else. If you like the results with surgeon A vs. B then go to that surgeon.

 There are many issues that go into making a nose appeared natural versus unnatural. There are several issues that can occur after a rhinoplasty procedure such as a poly-beak, an open roof deformity, and  a hanging columella that are a tip off to having had a rhinoplasty procedure. For more information and many examples, please see the video and the link  below