Back to laptops. It will be the rarest of individuals who cannot feel whether the stream of very warm to hot air that ceaselessly issues from the heat sink vent on a laptop has stopped. If it's on, even at idle, you will feel heat from this vent. A CPU/APU is never anywhere near to room temperature when running and the fan is always on, even if at low speed.
The most reliable way to tell if a laptop is actually off is to check with your fingertips or palm placed just beside this vent exit. If you don't feel anything the probability that the machine is off is as close to 100% as it's possible to get.
Most desktops are "noisy" enough that you can tell by listening if their fans are off. They also have such large airflow and multiple vent points that the temperature differential of air coming out doesn't feel that much different than ambient air temperature indoors. Laptops virtually always "feel hot" because of the confined spaces involved and the small fans involved, too.
Brian - Windows 10 Home, 64-Bit, Version 1803, Build 17134
The real art of conversation is not only to say the right thing in the right place but to leave unsaid the wrong thing at the tempting moment.
~ Dorothy Nevill