There is a rust trait out there. Not a health issue, just a red/orange (rust) tinge to the shrimp.
Some like the look of it, some don't.
If I remember correctly, the rust trait originated in Germany on OEBT's. RBT can have the rust trait if their line came from BTOE x OEBT (with Rust trait).
So not all RBT have the rust coloration.