Even if he didn't know, would his not knowing that Google tailors results per-user somehow make his other points worthless? That seems like a form of poisoning the well.

I looked up "poisoning the well" because I didn't know the precise meaning, thanks for the new phrase! In fact I'm not "poisoning the well" because a) My opinion was the one in question; Poisoning the well requires an audience and poisoner and more importantly b) I didn't introduce this information, the author wrote it himself.

Anyway regarding poisoning the well, check out the second example here: https://en.wikipedia.org/wiki/Poisoning_the_well#Examples "The text is written so obscurely that you can't figure out exactly what the thesis is (hence "obscurantisme") and then when one criticizes it, the author says, "Vous m'avez mal compris; vous êtes idiot" [roughly, "You misunderstood me; you are an idiot"] (hence "terroriste")."" Ironically, this does precisely describe the behavior of a commenter here, but it's not me. :p

Thanks for your response. What I meant was that him not knowing Google tailors results has no bearing on his gripes about

1. not being able to link to the original article,

2. Google favoring Google+ posts in search results overall,

3. and the Google+ interface looking and working terribly.

I used poisoning the well because it was a related ad hominem: you're saying him being wrong in this one instance means he is wrong in these other unrelated instances.

Hmm... I certainly didn't mean to say he "is wrong." Given many claims I can't verify, I give the person the benefit of the doubt: I can't say if it's right or wrong so I'll assume the author is right. BUT, once I see one assertion that I know to be way off or highly uninformed, I revoke that "benefit of the doubt" on all the other claims. As I said it's unfortunate, but I can't assume the other assertions are any more valid than the one I know to be wrong/uninformed.

Horse flogging, stop now: If you were to tell my that northern Spain is rainy in the winter and Sweden has long dry summers, I'd take your word for it (I know little about the climates in those countries). BUT if you then told me snow is rare in winter in the US Northeast, which I know to be false, I ask myself "hmm... could his statements about the other places be equally inaccurate? He has demonstrated he does not know what he's talking about vis-a-vis local climate trends." Do you see what I mean? I'm not saying anything he wrote is true or false, it's just called into question by a demonstration of ignorance on the topic.

In this case, it might make the overall thrust of the article - that G+ is reducing the quality of Google search results - worthless, because it calls into question his credibility with regards to his ability to assess that quality.

It's like Yelp reviews of sushi restaurants that start with "I don't usually eat sushi, but..." ... the points involved may still be valid, but the overal credibility of the assessment is seriously impaired.