When a journalist writes an article showing off his or her writing skills, vocabulary and worldly knowledge rather than sticking to the job of reporting. This is usually the case in an interview where the opinions and insight of the subject are overshadowed by the journalist's uncontrollable need to show off. It is when the standard of unbiased journalism becomes commentary when it is not supposed to be. In other words, it's all about the writer's ego.
The best example ever of "journalistic masturbation" can be found in the cover story of the LA Weekly Nov. 30 - Dec. 6 issue/ Vol. 30/ No. 2 "Dennis Kucinich Has Five Minutes For You" by Dwayne Booth.