On criticism: A critique?

This article offers useful advice on how to go about giving and taking criticism, but has certain flaws that the author should address.
The author tells us that following from a lack of objectivity in the observed world, there can be no objective measures when criticizing a work. He then develops on this statement by discussing the importance of understanding the intent behind a work when judging its worth.
Later in the article, he advocates critics to find admirable qualities in works which the critic may dislike. He says: "Your personal preferences only get in the way of providing the work and its maker... with useful information." This advice directly contradicts his belief in the lack of objective criteria with which to judge a work. Supposing for a moment that the intent of a work is clearly known and communicated and that multiple critics, regardless of their affinity for the work, can put aside "preferences" (subjective, of course) to address underlying attributes, this clearly indicates the presence of a more objective set of criteria for judging the work.
To take the author's example of a pan: imagine that a panel of critics knows it is a pan intended to cook meals, and made to last for a year, and one of the critics picks up the pan and the pan falls apart. Hey presto! Objective criterion for judgment: the pan has failed to perform its intended function. Of course, one could argue about the 'level of objectivity' of any set of criteria, but I've found that a discussion like that usually stumbles into relativism, and falls over on its face there. One could also debate the applicability of such judgments in the criticism of a creative work.
Regardless, the author does offer some sound advice on the giving and receiving of criticism. I strongly agree with his views on the use of not responding to criticism instantly, but rather taking the time to think about it, and asking for qualifying statements instead. Other parts, such as his recommendation to alternate between good and bad advice seem less pragmatic, considering that they could lead directly to the fabrication of insincere statements.