I've actually wondered the same before. To the best of my knowledge I've never heard anyone cite overflow: auto; as a negative signal compared to the amount of press display: none; text-indent: -9999px; etc. gets.  It very well could be abused just as badly though.  The only way I could think of an abuse-check would be to weigh the amount of text in the corresponding div against what a practical min-height of that div should be, but that seems a bit excessive.

I agree with Steven, it's come to a point where these css techniques have very legitimate uses and probably shouldn't be penalized.  Plus, there's plenty of other ways to accomplish the same thing, whether it's document tree manipulation or any other kind of rendering of a page after the crawable URL has been loaded. So at what point is it worth fighting such a thing?

edit: on a side note, what's the deal with those crazy underscores at the end of the URL? yuck.

Motava, here's a video where Matt Cutts discuses the nofollow attribute on internal links.  Generally I'd agree with EGOL and say it's a bad idea to place nofollow tags on pages that you do want followed in other locations.

You could get fancy and place the links in a subfolder restricted by a robots.txt file and generate them via ajax or javascript, but that's probably not worth the added effort.

Hey Jorgediaz, first off I think it would be wise to add the canonical tags specifying the primary URL for all of your pages, additionally it wouldn't hurt to add the parameter in question to your Google webmasters tool letting Google know to ignore your affiliate parameters.  You can find that in the Site Configuration settings under the 'parameter handling' tab.

I personally woudln't worry too much about the 'loss of link juice' since I think what Matt Cutts is talking about is more duplicate content that results from shopping carts that might serve up a very similar page based on a filter (such as re-ordering products by price).  In my experience affiliate links aren't the greatest in the first place, many are probably even using your publisher ID sending the link to an intermediary source for tracking purposes, so to recap, if it were me I'd add the canonical, add the parameter in your webmaster tools and leave it at that.

Hope this helps.