Depends on their character. A few meat-eaters will get upset, because deep, inside they know, it is not ethical. Vegetarians may look down on them, and that is what can start a fight. It is difficult. Vegetarians consume dairy and eggs and everything except fish and meat, it is not a huge step towards an ethical lifestyle only a small one. And a meat eater can be a more ethical consumer than a vegetarian, if he only eat meat once a week for example. Tell'em that is human nature.