A burger worth eating is worth eating plain.
For the better part of my hamburger eating life (which is the better part of my life as a whole) I put ketchup on virtually every hamburger I ate. It was only when I started looking at the hamburger beyond my home in New York City that I realized that ketchup was far from ubiquitous on hamburgers, as I had imagined.
In California, the "special sauce" that is perhaps the most defining characteristic of the Southern California model does contain ketchup, but the addition of mayo substantially changes the experience and makes ketchup unnecessary. In Texas, where beef is taken as seriously as any place on earth, ketchup is almost universally shunned. In neighboring Oklahoma, burgers with ketchup are derisively referred to as "Yankee burgers." At Louis' Lunch in New Haven, Connecticut—the claimed birth place of the hamburger—ketchup is banned from the premise and any attempts to smuggle some in will result in a ban for the culprit.
The more burgers I ate as a reviewer, the more I came to realize that ketchup was getting in the way of the distinctions between them. As soon as stopped applying the red stuff I discovered whole new worlds of flavor. Now converted, I try not to be too much of an anti ketchup zealot, but I find it hard on occasion. I was recently enjoying dinner at Minetta Tavern until I noticed a gentleman dousing a Black Label burger in ketchup. I had to restrain myself from berating him. The Black Label is a $26 hamburger that uses dry aged rib eye as its primary component. Would you put ketchup on prime steak? (The question is supposed to be rhetorical; if you do put ketchup on steak we need to talk) Why on earth would someone choose to cover up such a carefully crafted blend of prime beef with a such a sweet, overpowering condiment?
The answer, beyond fault of habit, is familiarity, which unfortunately in this case does not breed contempt. Ketchup makes every burger taste somewhat similar; it provides a common thread from burger to burger. It's a comforting familiarity that is quite the opposite of what I am looking for as a reviewer and a hamburger aficionado. I am looking for what is unique in each hamburger—I don't want to make them all the same. I want to enjoy each as a unique expression of burgercraft. And lest you think that my aversion to ketchup has something to do with my admitted burger purist tendencies, I actually think giving up ketchup will open up the palate for new condiment and topping possibilities.
It is not that ketchup does not have its place—it can certainly save a dry, flavorless hamburger, the type that isn't worth eating otherwise. But I would argue that mustard does the same thing and has a flavor profile that is more compatible with the savory nature of the hamburger. Of course, ketchup is implicit in many burgers—It is part of the recipe, as integral as any other topping. In those cases I will eat the burger as it is served, but given the choice I will always go without. A burger worth eating is worth eating plain.
Why not try leaving ketchup off the next hamburger you eat? If you don't try it without, how will you know if it needs it in the first place? Who knows; you might find flavors that you never anticipated and pleasures you never expected. And you can always squirt some on after if need be.