First of all, flip-flops = invention of the devil himself, designed to send as many souls to their eternal reward as possible as rapidly as possible.
You may have guessed that I don't wear them. There are two reasons for this, one of them being that I've never seen a pair that had any traction whatever when things got wet, or otherwise slippery, and I have an aversion to landing on my keister. Or my face. And yes, this from experience.
So while I have NEVER gone skating while moving anything on the ramp of the TH I've never owned, I have had footwear fail me on the traction front.