Why Your Reddit Replies Sound Like AI: 6 Tells to Kill
Here's a test I run on every founder who tells me their Reddit replies sound like AI even though they wrote them. I ask for the last three comments they posted. Almost every time, all three end on a punchy standalone line, at least one has an "it's not the tool, it's the workflow" flip in it, and they all sound like the same person in the same mood, whether the thread was r/sysadmin or r/smallbusiness. No em dashes in sight. Still clocked.
I build Social Cue, which finds Reddit, Hacker News and X threads worth joining and drafts a reply for you to edit and post. That means I've read thousands of AI first drafts and watched which ones Redditors pile on. The pattern is clear: the tells are structures, not words. Here are the six that get replies downvoted, how to fix each one, and the test I use before posting anything.
The em dash isn't the problem
The internet spent a good chunk of 2025 arguing about whether em dashes prove a comment was written by a machine. They don't. Writers who never touched a chatbot have been defending the dash all year, and they're right that it's a sign of edited English, not of ChatGPT. Word bans miss the point for the same reason: strip "delve" and "game changer" from a draft and it still reads like a slide deck, because the shape of the paragraph gives it away.
Reddit cares about that shape more than it used to. After Reddit's March 2026 policy post put name tags on registered bots and pushed suspicious accounts into human verification, users got noticeably more aggressive about calling out text that smells generated. A downvoted, reported comment doesn't just lose that thread. It feeds whatever signal Reddit uses to decide how visible your account is next time. So the fix has to happen before you hit post.
The six tells that get Reddit replies downvoted
These are the structures I've had to write explicit rules against in Social Cue's drafting prompt, because a language model reaches for every one of them by default. Each comes with a rewrite.
1. The "it's not X, it's Y" flip
"The problem isn't the code review, it's the access the agent has." Models love this because it sounds like insight. Redditors have learned to spot it as the single most reliable fingerprint of a generated reply. Just say the point once. An agent with prod keys is a different risk than one sandboxed to a repo, and that's the part I'd review. Same content, no flip.
2. Aphoristic imperative pairs
"Trust the diff less; constrain the blast radius more." Nobody has ever said that to a coworker. Paired imperatives with a semicolon between them belong on a conference slide, and every Redditor who reads one hears a keynote speaker. Flatten it into one plain sentence about the actual thing in the thread.
3. The mic-drop closer
A short, punchy last line built to land. "That's the whole game." "Everything else is noise." Real comments end on a normal sentence, often a slightly boring one, because the person had said what they wanted to say. If your last line would work as a tweet on its own, delete it. The comment is usually better without it.
4. Rule-of-three lists and "the real question is" reframes
Three parallel items with rhythm ("faster, cheaper, and honestly more fun"), and openers like "the real question is" or "what nobody mentions." Both exist to sound clever rather than to answer. One specific detail beats three rhythmic ones, and a narrow, partial answer reads more human than a tidy summary. Answering only the part you actually know about is a feature.
5. Jargon as a flex
"Blast radius", "surface area", "orchestration layer", where "what it can touch" would do. Jargon in a reply signals that the writer is performing expertise instead of helping. The Search Engine Land guide to Reddit comment frameworks puts it well: your company is context, not the point. The same goes for your vocabulary.
6. The same voice in every thread
This is the one people miss. A model, and a founder in a hurry, answers everything in the same measured "insight" register: balanced, polite, structured, identical in r/devops and r/Entrepreneur. That sameness is the real tell. Real accounts have range. Sometimes you're plain and technical, sometimes dry and a little blunt, sometimes you leave a one-line joke because the thread earned it. If your last five comments all sound alike, you're defaulting, and so is the model that drafted them.
The same thread, three ways
Say someone in r/ExperiencedDevs posts that they've stopped reading the code their AI coding agent writes, and it's been fine. Here's the reply a model produces on its first try:
"Not reading the code" only works if you've bounded what the agent can touch: which files, which secrets, which external services. Trust the diff less; constrain the blast radius more. The scary part isn't unreviewed code, it's unreviewed code with unreviewed access.
Every tell in one paragraph. Now three rewrites, any of which would survive:
- Plain: "This holds until the agent has real access. Sandboxed to one repo is a very different risk from one that can reach prod and read secrets, and that's the part I'd actually review."
- Dry: "Fine until it has your prod keys. At that point 'I don't read the code' just means you find out what it did afterward."
- Funny: "sure, skip reading it, right up until 'let an unsupervised agent near prod' is line one of the incident report."
None of them reach for a thesis. Each makes one concrete point about the actual thread and stops. Which one you'd post depends on the subreddit's mood, and that's the judgment a human brings.
The delete test, and two more before you post
Killing the six structures gets you a reply that sounds human. Three quick checks get you one that's worth posting.
- Delete the product name. If the comment still deserves an upvote with the mention gone, post it. If deleting the name leaves nothing, it was an ad. This lines up with what every guide to replying without spamming says, and with the 90/10 rule most subreddits still enforce.
- Read it out loud to an imaginary coworker. Would you say this sentence across a desk? If it sounds like a slide, rewrite it flatter. Casual and slightly incomplete is fine. Polished is the problem.
- Check that you said one thing. A single sharp sentence or one genuine question ("wait, how does that handle rate limits?") is a complete reply. One to three lines is the default. Four is the ceiling unless the thread is technical and someone asked for detail.
And when you built the thing you're mentioning, say so in plain words. "I built this, so take the bias into account" is cleaner than pretending to be a neutral stranger, and Redditors reward it far more often than they punish it.
Teaching the draft your voice
The obvious objection: if AI drafts have all these tells, why use an AI draft at all? Because the blank page is what stops founders from replying, not the editing. A draft that already found the right thread and made the right point saves the twenty minutes; the sixty seconds of rewriting is where you add the detail only you know and strip whatever slipped through.
The part I care about is making that rewrite shorter over time. In Social Cue, every drafted reply sits in a local queue for your review, and when you fix one you can leave a note like "too salesy" or "shorter, and no closers." The plugin distills those notes into voice rules that go into the next run's brief, and a rewrite you're happy with can be saved as a before-and-after example the model matches next time. Runs on the Claude subscription you already pay for, so there's no second AI bill for the rewrites, and it drives your own browser rather than a platform API that can be revoked.
Honest limits: the first drafts still sound like a language model until you've given a few rounds of feedback. The rules above are baked into the prompt, but rules reduce the tells, they don't zero them. And you post every comment yourself, from your own account, because that is the line Reddit drew in 2026 between assistance and automation. Scheduling your own posts is a solved problem, and the Postiz and Social Cue playbook covers that half. Reach inside other people's threads is the half that still takes a person.
The checklist
- No "it's not X, it's Y" flips. Say the point once.
- No paired imperatives, no mic-drop last line, no rule-of-three rhythm.
- Plain words over jargon. "What it can touch" beats "blast radius."
- Vary the register to match the thread. If your last five replies sound alike, change one.
- Delete the product name. Still worth posting? Then post it. Disclose if you built it.
- One concrete point, one to three lines, end on a normal sentence.
Run your next three Reddit replies through that list before posting. My bet is at least one loses its closer and reads better for it.