Perhaps trickery was a misleading word. The point, which I believe holds, is that people think they are doing it because it is morally right, but they are actually doing it because it helps them; there is an ulterior reason. But you do not judge them by moral values. The moral values are false values, facades for the real values, impostor values. They do not make things right and wrong, they just stand as approximations of why things are right and wrong. But once we've realised why we have moral values, you no longer need to hold them. You can work out which things are helpful and follow them. Yeah, pretty much.
That doesn't mean it's not morally right. Your argument here seems similar to: "Why did you give that man money?" "To pay for this mars bar." "Ah, but you only got the mars because the taste feels good, so you didn't give him the money to pay for the mars bar, you did it to feel good!" "Ummm... I guess..." It's the Mars Bar argument again. Moral values are as real as any. Moral just denotes what context they are in. It's a bit like saying: "You don't want to pour gasoline over yourself and light that match, you'll get burned!" "Wrong! I don't care about being burned, I just don't want to feel the pain and have my body destroyed!" Adopting moral values isn't simply a matter of recognising which actions are demanded by our needs, it's a matter of psychological transformation too. Psychological transformation is a necessary part of the process. Being altruistic will be a miserable life if you begrudge every action you do - you have to build the psychology and aquire a taste for it, come to love it for the thing itself. Once you have aquired this taste for moral values as your needs demand, your interests have expanded to include things they didn't before.
I think your mars bars example is flawed. When we say we want a mars bar, it implicitly contains the assumption that you want to feel the pleasure of eating it (Mars should be paying us for this). When you say you are doing something because it is moral, the fact that it benefits us is not implicit. The idea of morality seems to assume that things are right and wrong in themselves, that morality is the ultimate justification. Once you realise that morality is not the ultimate justification, it is no longer really morality. It is just a code of conduct to be followed when it suits us best. If our situations were to somehow change to one where our code of conduct is no longer useful, it is to be abandoned. I keep getting halfway through my posts and then lose interest and just start repeating myself. Sorry.
