Ever since I announced the Steam release date for my game Son of a Witch I have been getting a lot of Steam key requests from press and Youtube/Twitch streamers. Many of those requests are actually fake: scammers just want to get keys to play the game for free or resell on sites like G2A. It might look like getting a single key to resell doesn't make sense, as it would earn them some small amount of money, but when you multiply that with the number of games coming out and the fact that they fake dozens of different accounts to get multiple keys for the same game, it does get substantial.
To weed out the scammers, a good approach is to check their YouTube channel profile and look for the contact e-mail in the About section. However, this isn't always enough. You need to take a close look at the channel itself, as there are a couple of ways they can make it look legit. For example, I had a couple of Youtubers whose e-mail address checks out, but when I take a look at the channel, it seems like the last video they recorded was 2 years ago. If you see @gmail, @yahoo (or any other freely available) contact address, it probably means that it's an abandoned account and scammers found a way to get access.
Another way to cheat is to buy fake YouTube views. I had keys requests from YouTube channels that seemed solid. 1000+ views on every video. You would give a key to such channel, right? Well, after looking at it a bit more, I started to see a pattern: every video had between 1000 and 1050 views. And somewhere in the list, there were gaps: videos with only 1-50 views. And there were no videos outside those two ranges. So, there wasn't any video with, say, 250 views, or 1200 views. This means that this guy usually gets up to 50 views per video and he just bought 1000 fake views for some of his videos.
Some YouTubers don't have an e-mail in their profile, but you can still do some sanity checks. The thing that I often do before even checking if the e-mail is correct, is to go to their channel and see what games they cover. If it's your typical channel with Minecraft-only content, or AAA-games only content, then chances of them actually covering an indie game are slim to none.
One of the approaches the scammers are taking currently is going the Twitch route. Unlike YouTube, it's impossible to get contact e-mail for a Twitch streamer. The scammers know you can't verify their e-mail, so you have to take the risk. But not really. There's a feature in Twitch called Whisper. This allows you to contact the streamer directly via chat. You need to have your own Twitch account to do this. I recommend you get a Twitch account anyway, so you can use it to get your game listed in Twitch game directory, so the streamers can mark that they are streaming your game and you can track that.