I have generally been fortunate to have avoided some of the review horror stories. However, I would say that my worst review was one during which the two reviewers noted two entirely different views on the manuscript - they did not merely disagree with types of revisions. Instead, one reviewer generally deemed it acceptable with minor revisions while the other reviewer made comment after comment negating my premises. Admittedly, I find some pleasure in taking critical feedback and strengthening premises if one can sufficiently refute them. This particular review, though, did not offer constructive feedback. It was a straw man fallacy, such that I felt almost certain that the individual disagreed with my entire perspective and remained steadfast to her or his own. 

We are all entitle to our own opinions and, in many ways, this is how manuscripts can become as strong as possible prior to publication. Serving as a peer-reviewer is also a role to take seriously as a service to the profession - one that should offer useful and actionable feedback to authors of all manuscripts sent for review, even if the topic is highly contentious or defies everything we believe or claim to know. This is how strong science makes it through, even if it takes countless submissions and revisions to eventually make it work. While relatively minor compared to other stories I have heard, I have taken this experience and allowed it to inform how I review manuscripts. It becomes a highly rewarding activity that instills humility, because no matter how much we believe we know or understand about a topic, there is always room for growth.