Eloquence and logic are not mutually exclusive. In fact, eloquence is ability to present logical thinking in a better and, often, easier-to understand, way. I think you are confusing magicians, con artists, swindlers, hustlers, little neighborhood crooks, and a few more with the skill and gift that eloquence actually is. You seem to think that anything that is laid out nicely must be there to get you somehow. It is not always the case. It really is not. Just like the truth which can also be pretty.
How did lawyers' personality characteristics end up here?