I appreciate your point of view, but I disagree with your conclusions. Let me explain.

  > If the idea is good you'll get the vote.

That's true of most submissions, but doesn't seem to be true of polls.

  > Nobody is going to withhold the votes in order to not give you the karma.

I think there will be people who vote and move on without thinking to upvote it. Because of that, I wanted to remind people to up-vote the submission.

However, there are people who resent being asked for up-votes, and I wanted to make sure they weren't annoyed by that. I don't want to annoy people gratuitously, and this is the technique I have. People who don't care about karma, whatever, won't care (mostly). People who do care about karma, whatever, have a means of punishing me for asking.

  > Polls usually don't get a lot of upvotes unless the poll subject is really good.

Exactly, that's why I wanted to ask for upmods - to buck that trend.

So here's a summary of my reasoning:

* Some people vote and move on without upmodding

* I want them to upmod so the item has a chance to get enough votes to be vaguely meaningful

* That means I need to ask for upmods

* Some people resent that, so I need some way they can punish me

* The "scapegoat comment" seems to satisfy that.

Interesting that informal karma bartering has struck up of its own accord. Probably a lot more goes on behind the scenes.