When covering one vector shape with another; if the edges overlap, the background shape's color is used as a (distasteful looking) pseudo-anti-alias effect on the foreground shape's edge, instead of having the foreground shape's color blend in with the color of whatever is outside both shapes. (Wow, I'm not sure if I made any sense describing this.)
I can cope with this happening within Illustrator, but why does it have to happen in any exported vector formats as well? For instance, when rendering logos in .EPS format, how do you deal with this annoying phenomenon? Is there any way to circumvent it without having to manually offset (trap?) the background object's edge so as not to get this undesired effect?
Choosing "Save for Web" in Illustratos seems to always render perfect results. But somehow (maybe someone can explain the technical reason) vector formats won't regard the behind-object to be entirely covered by the frontmost object (i.e. disregard the lower object's edge), but instead insist on "spilling" in its color onto the edge of the frontmost object.
To wrap it up:
I'm mainly looking for advice/approaches when dealing with this, especially within context of logotype crafting, where deliverables may often be requested in .EPS format, apart from normal bitmap formats.
EDIT: one thing I find interesting is that when doing "Save for Web" and switching between Art Optimized and Type Optimized, the latter will also exhibit this undesired phenomenon.