Read the lie as a green, amber or red light
Before deciding to slide the club under the ball, the instructor grades the lie like a traffic light. A green light is when the club sits lower than the ball so you know you can slide under it. An amber light sits acceptably but not as clean, so give it a go but you must be pretty good. A red light, such as a ball down in a divot or hole, is very hard to slide under and needs a different, trapped shot.
Channel: Dan Grieve
Watch official source at 35:55