Man, I wish this recommendation had come out years ago.
The one & only time I've ever done mouth-to-mouth resuscitation to a real-life human being was several years ago in my first month of work in a downtown GP clinic. Security had called up to inform us that someone had fainted & they were bringing up the lady. This was at lunchtime when I was one of two doctors on duty, the other one having gone out to lunch, & we were operating on a skeleton crew of clinic assistants.
As soon as I saw the patient's condition, I knew this was not a simple case of syncope, but that she was in cardiopulmonary arrest. She was blue, no pulse, no respiration, & probably had been in this state for at least 15 minutes judging from what the security guard told us.
Adrenaline kicked in immediately as I called for one of the nurses to help me give CPR & look for the crash cart which no one could find as the assistants in charge of "taking care" of the cart had gone out to lunch...so much for being prepared.
Anyhoo, given the urgency of the situation, I had no choice but to give direct mouth-to-mouth resuscitation while the nurse did chest compressions. Fortunately, the patient had a relatively dry mouth (could have been bad - use your imagination). Unfortunately, given that she had probably been down for at least 15 minutes, despite our continued attempts at CPR, there was no response. The ambulance medics continued CPR as they brought her to the nearest hospital.
Alas, this was not a happy ending.