It's not directly Steam Sales, but you cant add steam cards before steam is 100% sure its a legit game ;)

https://steamcommunity.com/games/593110/announcements/detail/1954971077935370845

"Instead of starting to drop Trading Cards the moment they arrive on Steam, we're going to move to a system where games don't start to drop cards until the game has reached a confidence metric that makes it clear it's actually being bought and played by genuine users. Once a game reaches that metric, cards will drop to all users, including all the users who've played the game prior to that point. So going forward, even if you play a game before it has Trading Cards, you'll receive cards for your playtime when the developer adds cards and reaches the confidence metric.

The confidence metric is built from a variety of pieces of data, all aimed at separating legitimate games and players from fake games and bots. You might wonder why the confidence metric will succeed at identifying fake games, when we weren't being successful at using data to prevent them getting through Greenlight. The reason is that Greenlight is used by a tiny subsection of Steam's total playerbase, producing far less data overall, which makes it more easily gamed. In addition, Greenlight only allows players to vote and comment, so that data is narrow. Steam at large allows players to interact with games in many different ways, generating a broad set of data for each game, and that makes identifying fake ones an easier task."

It still costs money tho, sure its not much but it adds up and I preffer to just save that for one good BTA from humble.