To me, there are 3 kinds of players in Dominions:
The Faithful: they stick to their word, and won't never break an agreement, even if it means putting themselves in jeopardy. I know such players exist, but I always assume they don't
.
The Defectors: these don't hesitate to break treaties or swindle their trade partners at the first opportunity, if they see an immediate benefit when doing so - even if the said benefit is negligible. These players don't annoy me much - their behavior may net them a small advantage in 1 or 2 games, but in the end they work against themselves. I hate to carry my own perception of a player's personality from one game to another, anyway you can't expect from someone to trust a guy who was 'reliably unreliable' in the past 5 games.
The Wise: these usually stick to their word, and can be relied on when trading. However they won't hesitate to backstab you when they think that'll give them a substantial advantage - typically shifting the balance of power enough so they increase their own chances to win manyfold. I think that in Dominions, nothing comes closest to an
oeuvre d'art than a skillfully planned and carried out backstab. So I tend to respect this sort of players immensely. Even if I'm at the receiving end of their treachery
.