Brands fail on Reddit for a simple reason: they arrive with a campaign and the community arrives with a memory. Someone always finds the old complaint thread. Someone always asks what you are selling. If you cannot survive that, do not post.
This is how to get traffic and sales without becoming the villain of the week.
Permission is cultural
Each subreddit has an advertising allergy with a different trigger. Some allow self-promotion on Saturday. Some allow it never. Some allow it if you have a 90-day comment history. Read the rules. Then read the last ten removed-style dramas in the comments to see the unwritten rules.
If you need volume, Reddit Ads exist and are labeled. Mixing unlabeled ads into organic is how you get a mega-thread with your name in the title.
The native content stack
Sales happen when a third party says "we used X." Your job is to be worth mentioning.
When engagement tools are appropriate
Use them to distribute native posts, not to fabricate love. A product launch recap that the community already likes can use drip upvotes so more of the community sees it. A "we're the #1 platform" post cannot be saved by any vendor.
Downvotes on false attack threads are a reputation tool some brands consider. They are also easy to abuse. If the criticism is true, fix the product. If it is a coordinated lie, document and respond in the thread like an adult.
Crisis protocol
Do not delete. Do not astroturf. Do not threaten legal action in the comments. Acknowledge, specify the fix, offer a path to the original poster, and follow through. Then let the community talk. Threads where the brand behaves well become case studies you could never write yourself.
Measurement
Track referral traffic, branded search, and the quality of incoming questions — not just upvote highs. A 2,000-upvote post that attracts the wrong users is a cost center. A 120-upvote post in a buying community that produces demos is the business.
Reddit marketing is slow reputation with occasional spikes. If you need only spikes, buy ads. If you need a channel that still ranks on Google next year, show up as a neighbor and stay.