I know where this has come from. Over the years, people who have had a higher returns rate and hardly keep any goods have, I believe, been told that their orders won't be fulfilled. I think this has only happened in extreme cases but if any of us were in charge of GemsTV and we had a few customers who ordered loads and sent back nearly everything each time, it makes business sense to decide whether it was acceptable to have our stock tied up and potential profits being hampered (bit extreme but if you've got 20 or 30 customers doing this repeatedly it will add up).
So on this forum I believe in the years I've been posting on here (7 or 8 years or so) I've seen about 3 people post who have said they've been "banned" from making future purchases due to the high level of returns. There are always two sides to a story so I don't know if these have been true cases but I do know that GemsTV used to check on the percentage of returns.
Hope that helps.