Artistic Proofs

I'll try not to dive too deep into the concepts of rhetoric, but I've been pondering about the formation of messages. We're all familiar with the three different techniques of discourse, namely ethos, pathos, and logos. On of these facets stands out the most when it comes to the development and dissemination of messages: pathos (emotional appeal). There are several different ways that message constructionists us emotion to stir the audience to action. The two that stand out the most to me are fear and humor. It seems as though most every tv commercial tries to bank on making the audience laugh, or at least crack a smirk. These types of ads are at their best during the Super Bowl, where football fans demand to be entertained by the in-between time frames of the game. On other hand, fear appeals try and strike a chord with the hearts of the audience. The message is constructed in  such a way as to make the listener seek refuge or protection from a perceived threat or danger. Both types of messages seem to at least have a minimal effect on consumers. But I just have to wonder how big of a role logos (logic) and ethos (expertise) play in the messages we, as PR professionals, we distribute.
I suppose it depends upon the context of the situation. Certainly in a disaster or crisis, people are not seeking comedy or satire. This is a situation that calls for logic and reasoning. This is a time for facts and future plans. The same can apply to political arguments. While emotion may play a role in politics, citizens look for expertise, character, and logical solutions to problems.
I think it might to be too much to hope for to expect that we all seek a combination of all thee modes of persuasion when listening to messages. Is it ethical to only appeal to emotions? It's a subject on which I've heard many debates. I guess I can only try to use logic and character in the messages that I create myself. But who knows, maybe I'll change my mind in the future.