One grift I've noticed with sponsored gacha streams is how the streamer always have exceptionally amazing luck. They always manage to pull a top-tier character very quickly, and then they spend the whole stream showing it off.

This kind of behavior is beyond predatory and should really be illegal, because it's obvious that the streamer is playing with far better odds than regular people.

Heck, if you want to keep it legal that's probably fine as well, but at least require clear disclosure when the streamer is getting improved drop rates.