My wife has a number of beautiful, yet very skinny, vases. On way too few occasions, I buy her flowers. One of my hang-ups to buying them has always been trying to clean the vases afterwards. Here is a great tip that I got from my mom to clean the bottom of skinny vases. Fill the dirty vase with clean water and drop in a few Alka-Seltzer tablets. The tablets foam up and will break-down the water stains!