I remember a series of posts JoJo did a while ago about the impossibility of getting things to stay suctioned to the wall in the shower. It's a problem I have periodically. My solution, fortunately, is much cheaper than hers, and it's quick and easy for me to replace the offending bottle-holding shelf if need be, thanks to a super-cheapo store just down the road that sells exactly the item I need.
However, before it becomes obvious that a new one is the only answer, there are usually weeks, or even months, when the suction cups keep failing and you have to stick the thing back up.
Of course, soon (but not immediately) after you put the bottles back on the shelf, at a time designed to give you the maximum shock (ie. in the middle of the quiet of night) the thing comes unstuck again and crashes down.
What I want to know is, given that the suction cups could not hold the shelf and contents in place, WHY THE HELL DO THEY STICK TO THE TILES HALF WAY DOWN THE WALL AND REFUSE TO COME FREE SO YOU CAN PUT THEM BACK WHERE THEY BELONG?