In Larry Niven's "Playgrounds of the Mind", there's a great piece he writes about how he one time took a bad review very personally. He then, to paraphrase as well as make a long story short, found out the critic who wrote such a scathing writeup was actually nothing more than a failed author.
To be honest, it sounds like the initial example provided by the original poster doesn't really meet this criteria (rather, it sounds the other way around) but still I think it's worth mentioning given that none of us are perfect (least, that's what I heard last) and as such mistakes will pop up from time to time. Or worse yet, VALID CRITICISM. Snarky bastards with their valid criticism. I don't want to hear criticism, I just want to hear how amazing my book was! Is that too much to ask?
I think the only way to safely approach criticism is to approach it humbly; to look at it for what it is. Evaluate whether it is valid or useful, and if necessary affect changes. If not, then thank them and move on. I worked for 10 years in the technical support industry for internet support via phone. One statistic that has stuck with me is that only 4% of customers actually call in to complain. The remaining 96% O_O will literally just disappear as they cancel never to be heard from again. Translating to an author's point of view, the author should be genuinely glad to hear that someone has found something which can be fixed, which might improve the experience the other 96% might not have mentioned when they decided to nix this guy off their 'must have' list.