Except it turns out they're not "sucker-footed" at all. They actually secrete a sticky fluid, and that creates the suction-effect.
Leading us inevitably to marvel at the cleverness and willpower of that first genius-bat, who first conceived the very notion of doing this, then strained to start the fluids... well, to create them in his body in the first place, by willpower; and then to start them flowing.
Then think of the thousands of generations over millions of years as insufficiently-but-slightly-sticky fluid seeped out uselessly, tripping the bats up but not really sticking. "Hey guys! Look! I think... I think I...." Bonk! "Ow."
Amazing! In fact... incredible!