Hilary, we too always resist buying a Poinsettia at this time of year. This is partly due to a visit I paid many years ago to a wholesale nursery in UK that produced thousands of these plants for sale at Christmas. They fed them a growth retardant in an effort to keep them all the same size for shipping off to the retailers. Once they no longer received this, and had been sold on to the public they obviously reverted to normal and began to grow leggy and less attractive. After the festivities were over many found their way to the trash or the compost heap.
One of the other things about this nursery that I found interesting was the staff they recruited to do the everyday watering of the plants. Each of thousands of pots had to be watered individually and by hand. This task was carried out by a team of workers, all of whom suffered from General Learning Disabilities. They were taught how much water to give to each pot while at the same time inspecting the plant for any signs that it may not be growing correctly, in which case they pointed it out to a supervisor. This raised certain points about whether or not this was a case of exploitation. These people, who many considered to be unemployable, had a job and were paid the going rate for it, a job that was so repetitive and boring that no-one else wanted it. It gave them a purpose, they had somewhere to go each day instead of being at home with nothing to do. They could interact with others. They were contributing to the family income. As I said this was many years ago and I have no idea if this nursery still exists or still follows the same employment principal in these days of Political Correctness, etc.