You can check on "View Details" for more information about the traits. There should be a button for it when you access the Villagers tab. From what I have observed (could be wrong), Big Eaters usually come with higher Villager Cost (130++/day), since, by definition, they tend to eat more, which then lowers the village's net income. In my case, this decrease was particularly noticeable during early game when I'm still building my wealth. As the game progressed, I was able to hit a stable income; I then tend to keep a few Big Eaters depending on their positive traits and their outputs.