Firstly I will say that I see foods from a scientific biological veiwpoint. We are evolved as gereralist animals capable of eating many different foods and so are not perfectly adapted to any one of them. All foods are trade-offs between different factors. Some of more, some of less benefit. It is the overall cost and benefit that is more important.
Seeing foods as good or evil can lead to cognitive discordance and confusion. For example, research or experiance that finds benefits to non-paleo foods or that finds downsides to very paleo foods must be explained away and causes uncertainty. But if all foods have some positives and negatives this is easier to understand.
However I can also see benefits to this way of thinking if it helps you avoid foods that are bad for you.
What do you think? Are foods good and evil? Do you find it useful or not to think about food this way? Do you believe there is any perfect food? I am interested in how other people here see this question.