The concept of "hot" and "cold" slots refers to machines that seem to pay out frequently or not at all

https://www.scribd.com/document/883762465/Memorable-Experiences-from-Iconic-Gambling-Enterprise-Slot-Floors-All-Over-The-World-151572

The suggestion of "hot" and "chilly" slots refers to machines that look to pay out oftentimes or by no means, besides the fact that these traits are at last random.