The first time As a male, is it acceptable to wear black nail polish at work? made it into the reopen queue, it was unilaterally kept closed by a moderator. It now has 3 more reopen votes.
It was closed as opinion based, but it is no more opinion based than the well-received question Male wearing earrings in workplace (South Asia) If that question is on-topic, I think the nail polish question can be salvaged. Men wearing nail polish is very trendy right now, (and it's not a brand new trend) and I think having answers to the question "Is it acceptable at work?" would benefit men working in areas where the workplace norms are more fashion-forward.
This is Dave Navarro wearing black nail polish in 2014. If the author had suggested he wanted to wear hot pink, I would be more likely to have thought they were trolling, but black is the most conventional color for a man wearing nail polish.
I know most people think of "the workplace" as a building full of cubicles and computers and people dressed in "business casual". I don't think questions about other types of workplaces should be off-topic just because those sorts aren't the most common.