Plants being living things, and you go by top growth to estimate the overall health, sometimes it can happen that customers get less than ideal plants with roots or other issues. In a commercial nursery, they are bound to have bugs and disease as well as genetically weak plants.
I just don't think vendors send crappy plants intentionally, although some seem to care less about quality.
This is why I do not mail order. I have to see and pick myself.
Take pictures as proof and talk to them if you get a plant with problems.
How vendors respond to this situation is what matters the most to me.
Getting a crappy plant ( happened to me a few times and so I don't mail order any more.i have to see what I get, prefer to examine them myself. No surprise this way or hold grudges against anyone) happens. It's the customer service and honesty of the business that makes a difference.
Orchid limited ( since it was mentioned lately) has an excellence customer service and responds very well.
Others like Normans, well, we all know.