It goes both ways.
There are advantages to taking risks in general - so if you sign NAPs with people, and gamble that they'll keep them (which is generally what I do), you're going to be in better shape in those games where it pays off.
OTOH, if you have a reputation for *rarely* breaking NAPs, this may be to your advantage since suspicious neighbors will waste troops guarding their borders with you. If you break them a lot, obviously they won't sign NAPs with you at all.
One of the enjoyable things about MP dom3 is the great diversity in strategy and approach. Any effort to "enforce" honorable play risks jeopordizing that.
As for lamers, I'd support a list of quitters 100%. All's fair in love and war, but if you quit too much (which is obviously open to interpretation), I'd like to know.
But I think any such list is invariably going to devolve into a recrimination-filled flamewar; this discussion has been very civil so far because the one person who's name-was-named happened to have a good sense of humor about it.
As for anonymous attack spells - if someone casts an anonymous attack spell at me, and I know it was them, I attack them. Likewise if someone starts walking void spectres through my territory. I strongly oppose "legalism" in dominions3 - the ingame communications aren't stored, and I'm not going to go over my ingame diplomacy with my lawyer. I'd much rather deal with someone who occasionally breaks their treaties than someone who tries to weasel around with what they do and don't mean.
Finally, as an American, I reserve the right to attack anyone who has both the intent and ability to acquire anonymous attack spells which they might cast against me
.