I have only recently begun taking review tasks seriously as a responsibility that comes with being a fairly high-scoring participant at this site—prompted in large part by tchrist's inspiring Meta post, How can we encourage more folks to edit?
I came to EL&U from a background in copyediting, so I have a fairly strong sense of how to improve questions and answers while remaining true to the intent of the poster. But what I don't have is a shared standard regarding what constitutes a legitimate question or answer; and in the absence of that, I apply my own standard, which appears to be considerably broader than the standard some other users have. I hope that my judgment hasn't led me to endorse bad edits of the type that Mari-Lou A rightly denounces in her question, but it has led me to try to upgrade and preserve certain questions and answers that others might prefer to see rejected out of hand.
In the brief time that I've been vetting suggested edits, I've seen many instances where the editor simply grafts an unrelated opinion onto an exiting post, or makes alterations that are irrelevant to the quality and clarity of the original post. These I vote to reject. On the other hand, I've seen enough positive editing efforts in the queue to conclude that such contributions are probably, on balance, beneficial to the site. The key to making the system work is for the people doing the reviewing to take their job seriously and not to give glazed-eyed approval to everything they see.
I am leery, however, of the idea of punishing "bad" reviewers—particularly reviewers of first posts, late posts, and possible low-quality posts. Because our standards vary so much from person to person, and because those standards reflect differing views as to the types of questions that should be welcomed (or tolerated) at EL&U, I think that threatening reviewers with punishment for being insufficiently discriminating in their approvals is problematic and potentially counterproductive.
It might make more sense for a moderator who perceives a problem with a reviewer's laxity to send the reviewer a tactful note suggesting that he or she consider either adopting a more stringent approach or leave reviewing the queues to other users. After all, I imagine, people participate in such review tasks mainly out of a sense of public-spiritedness, and not from a desire to gain a handful of obscure badges. I know that if a moderator were to tell me that my standards were so much at odds with those of the reviewing majority that they would prefer that I stop "helping" with review tasks, I would readily comply and go back to focusing on the more enjoyable tasks of asking and answering questions.
If we assume that reviewers (and editors) are participating in a spirit of good will, we can help each other contribute to EL&U in positive ways, and avoid needless conflict and hard feelings.