Clownie, in the game you were talking about, Carthage won.
I think the reason why appeasement is generally a bad idea is because it often results in the player you try to appease to be in a strong position to stab you; and you don't want any other power in a strong position to stab you. This may explain the counterintuitive idea that trying to appease a person can increase the chances of him attacking you in the future.
That said, there are situations in which appeasement is a good idea - namely situations in which you can afford to give a supply center, but in which it is very important that other players will do what you want them to do. An example that I can think of would be in
gameID=180969. In 2001, I (Brazil) offered to support USA into Colombia and I asked nothing specific in return. However, this helped me greatly diplomatically. It would have been very logical for the alliance of USA and Quebec to come after me shortly, but I managed to prevent that by framing myself as their 'third ally'. And when I later stabbed USA when his units were trying to attack people in other continents, he didn't see it coming from the guy that earlier gave him a supply center for free.
Another important aspect in appeasement, I think, is how you frame it. I don't think it is good to make it sound like a buy off deal, because then people will just think you are a bad dealmaker (and maybe become greedy and want to try what more they can get from you). If you however make it appear that you offer them a territory just because you like them and because you are a good guy, the other party is more likely to see you as a valuable ally.
Now about an other counterintuitive social mechanism that I have experienced. I am talking about world games here, since these are the only press games that I have played (here). When I am a small nation, I tend to be more honest and trustworthy than when I am dangerously big and can more easily handle wars with multiple people. That makes sense to me. But when I am big, people seem to be more prone to my suggestions than when I am small. When I am small, I am often wondering why people won't listen to my well-meant advice, and when I am big, I sometimes wonder how I manage to use other nations as puppets and why the other people don't realise I am solely using them for my own benefit.