I was skeptical about them at first, then my oldest daughter used them and I couldn't get over how white her teeth got... so I tried them for myself. I used them as they say, twice a day and in 10 days my teeth were so white that I get comments all the time about how pretty my teeth are... and I am a coffee drinker and a smoker. They worked great on me... and I didn't mind them at all, I didn't find them too gooey or messy, as a matter of fact I thought they were super easy to use.