Audio sounds oddly distorted https://clips.twitch.tv/TangentialObliqueLobsterSaltBae
https://clips.twitch.tv/CharmingBashfulAlfalfaRickroll
https://clips.twitch.tv/NaiveKindGorillaGivePLZ

(Disclaimer: These were not recorded on or uploaded from my computer.)

In the 1st video linked above, the water sloshing sounds heavily distorted and the same type of "noise" heard throughout that segment of the clip can be heard periodically throughout this person's videos, including the other ones I linked. 

I've been trying to help this person hear the problem with his audio, but he's not hearing it and I'm not entirely sure what the cause of it could be or how one could even describe it. 

EDIT: He switched to different broadcasting software and finally hears how bad it sounds now. Now we just need to know the cause.
It's mono, not stereo like one would expect, and it sounds like exacerbated compression artifacts to me, like in the difference signal between the stereo channels of a lossy compressed audio, but I'm not sure if that explains everything.

Given that he uses an external mixer for recording, there may be a simple explanation: He has connected a stereo cable to a balanced input of the mixer. The balanced input will typically take the left channel as "hot" and right channel as "cold", and will effectively see the mono difference signal: hot minus cold. He should use a stereo to 2x mono splitter cable, or use a stereo input in the mixer if available.