Macbooks are the worst, they don't even HDD led, or even "switched on" led!. Quite often, I can't tell if it's on already and coming back from sleep, or do I need to press "Power" button again. What a frustrating design.
You want to know what your stuff is doing and the reasoning behind the suggestion was litteraly "lets do it like Apple".
If a Macbook is asleep, it will just wake up, you'll see the keyboard light, there is no need to press the power button.
If there is a need to press the power button it is because the machine is off. Don't worry, it will make a distinctive and iconic sound once it is not off and display, you guessed it, a white apple logo on the screen.
What circumstances lead to your confusion about its state? I can't relate!
(It’s interesting in itself to track the history of power/sleep lights on MacBooks, since as far as I can remember they only turned on in the case where the internal display is off, or when the laptop was sleeping (pulsing light). Jony Ive even talked about it in the Objectified documentary: https://vimeo.com/7827217 )