For the second year, I have used these to secure lights on our front gate (white vinyl) which gets opened and closed several times a day.  We live in Oregon and Christmas is a very rainy and occasionally snowy time, but we've had absolutely no problem keeping the lights exactly where we want them in a very exposed location.  Last year I removed the hooks when I took the lights down.  This year, I am leaving them on at least for a while to see if they will last through the year.  They are clear so they are practically invisible on the gate.  I did follow the instructions exactly and cleaned the gate with alcohol and made sure it was completely dry when I put them on.