Human aesthetics can grow very subtle, many layers beyond naive sense impressions such as salty and sweet, melodic and upbeat. A subtle aesthetic can be a valuable cultural tool for evaluating quality of necessary physical and cultural items. An old cattleman possesses an aesthetic of cattle that cannot be communicated in a checklist; he will not be cheated easily. Tribes with sensitive aesthetics will not be bought off with glass beads for long.
In modern life, our aesthetics commonly protect us from threatening information. When we tune out or turn off a stream of information, we often do so in disgust. Pleasurable streams of information attract our attention instead. And what renders information streams pleasurable or disgusting is the aesthetic we have absorbed and created. Aesthetics, as memetically evolving items, are not "interested" in protecting us especially; they are interested in protecting themselves. They are old cognitive tools, and they are very useful, but at the same time, they tend to be conservative and to defend themselves from memetic threats.