Bad Biology by Berlin

Many writers these days tend to be overly cautious and tag every little thing, particularly when it comes to potentially triggering or problematic content, regardless of how much or little that content is featured in the fic. While thorough tagging is greatly beneficial on the whole, it can sometimes be hard to tell the tone or intent of a fic and how much weight you should put on those warnings from just looking at a list of tags.

"Dead dove: do not eat" is a flashing warning sign that, not only will potentially triggering or problematic content feature heavily, it will also be presented and framed with little to no authorial commentary or judgment. It's saying: "I hope you're prepared to read something fucked up because that's what you'll find here and I'm not justifying, moralizing, or apologizing for it. You have been warned." This should be used in conjunction with specific content warnings to indicate the exact flavor of fucked up you're going to encounter, but even if someone chooses not to clarify in the tags for some reason (a controversial choice, to be sure), it's still a warning in and of itself. DD:DNE is not entirely meaningless without other tags, it's just more thorough and informative with them.

Consider two fics tagged with rape/noncon, one with the DD:DNE tag and one without.

The fic without the dead dove label may just include discussion of noncon that happened to a character in the past, the noncon may occur in the fic but be glossed over and not described in detail, or the noncon may be dubcon at worst. Everyone has different thresholds for certain types of content, so some people may still choose to warn for it in these cases. I'm not attempting to pass judgement on whether or not the noncon warning should be used in that way, but it happens regularly and it can make sorting through tags to find what you're looking for complicated.

The fic with the DD:DNE tag? That's a Rape Fic. You can pretty safely assume the noncon is going to be a major component of the fic, it will likely be explicit, you won't be spoon-fed any morals about it, and it probably won't have a conventionally happy ending.

Not having the DD:DNE tag obviously doesn't mean that a fic does NOT contain dark or problematic content, as not everyone chooses to use it, but including it essentially guarantees it (at least when used correctly). This can be very helpful for anyone specifically looking for something angsty and awful to wallow in, while allowing others who aren't interested in that to safely avoid it.

Because of its inherent connotations, "dead dove: do not eat" should NEVER be used as a generic call to "mind the tags." If you add it to your non-problematic, 100% consensual fic because you happen to include an unusual kink or whatever, you WILL scare away readers because they WILL assume you have a dark untagged twist in there somewhere.