Review on NeverRust Stainless Steel Double Suction Hooks - Ideal Vacuum Hook for Towels, Robes, and more on Flat Smooth Walls (2 Pack) by Bishop Terry

They're good for what they are, well made (tough plastic with a metallic finish but they don't feel as fragile as some products ) and the pad is made of good gecko pad material and the clamping mechanism makes sense. The only problem is that they are limited by physics and therefore only work really well in ideal situations. They probably work well with glass or a mirror, but all the smooth tiles in our house are porous enough that after a few hours or a day or two they lose suction and fall off. Smooth walls painted with enamel suffer from the same problem. Basically, if you have a really smooth surface to attach them to, they're probably great, but far from perfect, and they'll fall off within a few days at most. However, I don't think you'll get any better with a non-harmful, purely suction-based solution. It's fine for this type of solution, but most installations require more permanent solutions like real glue or screws/nails, things that damage the surface for stability/permanence.