When my 88 year old dad had the stepladder slip out as he was cleaning the gutters over the patio he got a bunged up shoulder and an ambulance ride to the ER. When I came out to visit and tipped the same extension ladder in the same spot to clean the same gutter...yep the feet of the ladder slid out like the bricks were an ice rink. Fortunately I was only 58 and quite robust; I rode it out and only bounced a little off the bricks. Damage done to my ego but the body was mostly intact.

I had assumed of course that the old man was just getting awkward, never thought for a moment to check out the slimy surface of the bricks or the slick feet of the ladder;)