Simon Veksner had a good analogy on his blog about subjective nature of advertising arguments:
Our debates are more like one person saying “I like tomatoes” and someone else says “I don’t like tomatoes, I prefer avocados.”
To continue with avocadoes and tomatoes, there are two types of arguments in advertising context:
1. Arguments about preference
I like avocadoes and you like tomatoes. When asked the question which one tastes the better, we are both right. Then we should evaluate does our view reflect target audience at all. This is something people tend to forget: you are almost never part of target audience. It´s nice that you like avocadoes, but that does not say anything If it comes to a fight, it usually ends up that the one with loudest voice or biggest title wins. You are essentially arguing about what feels right.
2. Arguments about facts
Sometimes the selection should not be subjective, but can actually be objective and based on facts. If we need to select the item having more fiber, we should select avocado (7g vs. 1.2g in 100g). There is no question about that. If we are asking which one of them is healthier, the question is trickier. If we agree on variables we compare, we can come to a conclusion with that question based on facts. I.e. if we agree that fat and calories are bad, we should select tomatoes. If we emphasize magnesium and vitamin A, we should go with avocado. If it comes to a fight, facts should win. You are essentially arguing about what is true.
Both of these argument types are ok and I always enjoy debating and fighting about ideas. The frustration comes when you argue about facts, but your opponent still bases her view on preference (and fails to see that). Disturbingly often people dismiss the obvious facts because of their past experience or shaky anecdotal evidence. That is fine if you are arguing about the taste of avocadoes and tomatoes. But if we want to select the healthier fruit*, you cannot base your decision on the “fact” that you don´t like the color “green”.
Sometimes it is not also about choosing between avocadoes and tomatoes. You can also try making guacamole.
*Which brings us to another debate: are tomatoes fruits or vegetables (I hope that no one has that argument with avocadoes)? The answer depends on from angle you are approaching it. Scientifically both avocadoes and tomatoes are fruits. Naturally they are used as vegetables in cooking. In US Supreme Court the latter view won, based on the ways tomatoes are used and the popular perception about them. Good reminder that you have to always reflect the facts to your target audience´s perception of them.