My wedding flowers were HORRIBLE.
When I selected my bridal and bridesmaid bouquets, the floral consultant said she would sub a few flowers with comparable ones that were in season. When my bouquet arrived at the church, I was horrified to see what they used in place of the "out of season" flowers. They were the cheapest flowers and looked NOTHING like the ones in the picture.
Also, most of the boutineers wilted within a few hours of delivery and were not properly labeled.
NO LIE...I RECEIVED SO MANY DOUBLETAKES AND STRANGE LOOKS WHEN PEOPLE SAW MY BOUQUET. I actually still have friends that periodically say "Well, now that the wedding is long over, I can say this...What the heck were you thinking when you chose that bouquet?!?" Embarassing.
It was definitely the lowlight of my wedding, and thankfully, I opted for candleoberas at our reception table in leiu of flowers.
This was almost six years ago, mind you, but I've heard several stories of complete flower mix ups, poor substitutions, etc.