In classical rhetoric, the tropes and schemes fall under the canon of style. These stylistic features certainly do add spice to writing and speaking. And they are commonly thought to be persuasive because they dress up otherwise mundane language; the idea being that we are persuaded by the imagery and artistry because we find it entertaining. There is much more to tropes and schemes than surface considerations. Indeed, politicians and pundits use these language forms to create specific social and political effects by playing on our emotions.
Trope: The use of a word, phrase, or image in a way not intended by its normal signification.
Scheme: A change in standard word order or pattern.