Professors Jeremy Yip and Maurice Schweitzer (Wharton) took the time to examine trash-talking and its scientific effects in certain situations. The premise to "conceptualize trash-talking as competitive incivility" led to some expected results, frequently noting that the targets of trash-talking not only become very motivated (usually to win or succeed), but that sometimes they become so motivated that they're likely to engage in unethical behavior to win. Under this premise, trash-talking becomes a high-risk gamble by the talker: whereas the hope is that the method "gets into the head" of the talkee and gives an advantage to the talker, success is not only not guaranteed, but the talkee may look to do whatever it takes to make the talker lose, even if that means enacting some sort of harm on the talker. Their motivation is to see the talker lose rather than see their own rewards of victory.
In short, trash-talkers are now responsible for boosting their opponent's motivation and performance, thereby facilitating their own demise within the competition.
Other smaller points made within the study show that creative tasks (as opposed to constructive tasks) are actually completely disrupted and never fully realized as a result of trash-talking. Whereas solving a math problem that only has one concrete answer is considered constructive, creating a piece of art or another project where success is more in the eye of the beholder is creative, and therefore the real victim in situations with trash-talking.
Trash-talking also exacerbates conflict and promotes unhealthy rivalries, which can lead to other competitive behavior that has the potential to be detrimental. Consider the trash-talking that goes on between rival college football fans. The rivalry that brews as a result of such a tactic can lead to unimaginable and ridiculous conflict, rather than seeing someone for his/her character and not judging that person based on their team affiliation.
All in all, is the risk really worth the reward with trash-talking?