I see London. I see France.
This morning a for-profit blog whose RSS feed I paid cash money for linked to a commercial and, now, I'm furious.
I know. The obvious question is "who cares what I think?" My reply is that this point is bigger than my penny-ante ego and my satisfaction with a well-trafficked technical website. This is about a dream that we (whoever "we" are) stop multiplying the presence of commercials in our lives.
If you have a blog that even pretends to entertain, inform, or educate and you are a blog (and not one mouthpiece of a many-mouthed for-profit corporation), don't build content by linking to advertising.
If you have something to say about that advertising, some analysis or even corroboration, fine. I don't think product advocacy is a problem. But if your link to an advertisement is motivated by the idea that you enjoyed watching the advert and you think others might, too, you have become a tool of corporate interest, so hypnotized by consumer culture you no longer can tell the difference between fill and content.
At the very least, explain what you find interesting about the advert. Analyze its visual frame, comment on the technologies used to produce it, consider the emotions the advert elicits. It's not so hard to do. When you link to a(nother) company's commercial and stop right there, you've done nothing except extend an advertiser's reach.