Let's discuss the definition of Ethical.
One way I clear up confusion with definitions is to ask whether or not your argument or definition would make sense in another language. After all, if it's an English only issue, then you are talking semantics, not logic.
Ethics is a code of social behavior based on a concept of right or wrong, morals is a code of personal behavior based on a concept of right or wrong.
Example, you ask? Ok. Easy. Lawyers have a code of conduct that involves not disclosing the wrongdoing of a client (unless a life is in immediate danger - ie a believable threat to kill or do serious harm). Morally, we would be expected to report someone who has admitted guilt to a serious crime, but ethically, we (lawyers) cannot because by doing so it would undermine the legal system. Doctors run into issues like this on things like abortion and suicide, and priests with confessions, and so forth.
The point is that a Ethics are a social or external set of rules and morals are a personal or internal set. Yes, it's great when the two are the same, but sometimes it doesn't happen, nor should it.
Want an example of that? Morals include religious beliefs. What happens when those morals are imposed on a legal (ethics) system?
Sometimes you get good things like anti-slavery laws, sometimes you get things like the Taliban and the Spanish Inquisition. What happens when you impose ethics on morals? Sometimes good things, like freedom of religion, and sometimes bad things like Nazism and Communism. The point is that the two are different, and failure to recognise this causes a lot of harm in the world.
You can be ethical and not be moral, and you can be moral but not ethical. Just because you follow all the rules doesn't mean you are a "good person", anymore than breaking some rules automatically makes you a "bad person". The world is complicated. Get used to it, it gets worse as you get older.
But Ian, we are talking about SEO here. Ok, when you agree to play a game you agree to play by the rules. Don't like that, fine, but it's not ethical. By playing by the rules I mean "big picture" rules. Regulations don't usually count. Just because Google suggests that SEO's offer a moneyback guarantee doesn't mean you are unethical if you do not.
But the purpose of an effective search engine is to serve searches. That's it. Not maximizing your advertising dollars, not sending people to spammy sites, and not tricking people into thinking your site is more relevant to their search than it is.
This is ethics. If your personal moral code suggests that people should only be sent to sites that have been approved by your local church, synagogue, or special interest group, then that's a moral issue and is different from ethics. You can trick people for what you believe is their own good and still be moral (unless your personal morals prevent it) but you can't call it ethical. And doing it for money or fame is unlikely to even be moral.
If people continue to have problems with this because they were brought up without being taught clearly about morals and ethics, then by all means use different terms like Code of Conduct or Search Engine Approved Business Practices or white/black hat or whatever. Just don't pretend that thay are the same and then base your arguement or justify your behavior on it.