Interesting point you've made Fish, eh? No, I'm not Canadian, but I think it's interesting how the "eh" is added by many Canadian speakers. In fact, because I've lived most of my life in a state that borders Canada, I often use this myself.

But anyway, having thought about it more and researched it a little, I'm thinking that perhaps Bernie is looking more for the modal tag to the statement rather than the affective tag. The modal tag is used to ask for confirmation or information about that which the speaker is uncertain. Whereas the affective tag has the function of either softening or facilitating.

So, to determine the correct tag we must first know what kind of tag Bernie is looking for - modal or affective.

For more information on this, along with the rather interesting aspect of how it plays out in terms of gender, you can follow this link:
http://itre.cis.upenn.edu/~myl/languagelog/archives/000873.html

Well, I hope I haven't muddied the waters too much, have I? I imagine that some people would find this to be a rather mundane subject; albeit, personally I think it's great how that which is seemingly mundane can often be more complex than how it appears on the surface. Furthermore, by not allowing ourselves to be overwhelmed by the mundanity of a thing - that is to say, not considering it "underwhelming" - we can remove restrictive elements from our thought processes, can't we? If nothing else, this would make us better listeners, wouldn't it?