There's a statement on GameSpot responding to postings on the GameDealsMeta subreddit, as online game store Green Man Gaming denies accusations that some of the keys they sell are shady "grey market" keys, though their description of these being acquired "responsibly through authorised third parties" helps understand where these concerns originate. They respond to accusations of shadiness thusly: "We find the research carried out by the Reddit Game Deal mods has been subjective or inaccurate. We know they share the same aims as we do; to offer customers great value on great games, so it brings us no pleasure to publicly state - they are wrong." Here's more from Paul Sulyok CEO Green Man Gaming:

We reiterate that we source our keys from a range of over 400 publishers, developers, and distributors to meet customer’s demands on a title by title basis. Let’s be clear here; there is a difference between being an authorised retailer for some titles, and being a retailer selling keys that have been sourced responsibly through authorised third parties with revenue going back to the publisher. If a key unlocks, it is an authentic key. This isn’t a perfect science as human error can affect the supply chain. Where possible, we work directly with publishers and distributors to make sure customers have the very best experience with us.

Whenever things outside of our control have happened, we have instantly and fairly tried to make it right. We accept that we don’t always get it right, and we are sorry for any inconvenience caused. We’d like to take this opportunity to thank our customers, the Reddit Game Deal community, and everyone who has supported us.