There are usually tricks to getting some of your cut flowers to look better and last longer. The best time to buy lilies is when most of the buds are closed or are just beginning to open (which then allows you to see the color of blooms). Purchasing at this time will get you a longer period of display with them.
Once a flower bud has opened enough to see the dark anthers, it's a good idea to remove them from the flower by pulling them off. Doing this will ensure that no pollen will fall off and land on the petals, which will discolor them. It also helps prevent any pollen from falling off and causing an unsightly and hard to remove stain on nearby fabrics, the lilies may be placed near. If some pollen does get on fabric, do not try to remove it with your fingers because your natural oils will just cause the stain to set, causing more damage. Use tape to remove it - a piece for each time you need to touch the fabric until all the pollen is gone.
Even though lilies symbolize purity in art, that is not always be the case in reality. -J