Apparently it's very common for these shops pretend to be reviewers, request multiple keys and sell most of them.
That is a valid reason to revoke a key, although I've only heard of misused keys being revoked on several games.
If devs sell keys before launch date, they generally sell through websites that support pre-order (buy now, get key on release date). If you see keys getting sold ahead of launch it's a safe bet to say those were either review or giveaway keys that weren't meant to be sold.
Here's a vid of 1 developer explaining their story, of this exact thing happening.