It specifically is about looking unapproachable, angry etc, when the person doesn’t feel any of those emotions (hence the “resting” part, like resting heart rate). It means someone who is having fun but looking differently too. Bitchiness or shittiness doesn’t factor in at all - the “bitch” in the name is a metaphor.

If you read into it, the video is misleading and the bulbs aren’t as good as it claims. They don’t go out but they suck when it comes to the light they produce