There's a shop in Bridport that sells shed loads of such like rugs, so like you do, you pop in to have a chat.
It turns out they wash them all in a bath, nothing more technical than that and just keep going until the dye run stops.
All said as they buy then sell I guess it doesn't matter so much if they really duck one up, whereas we are in a different situation.
"Yes Mrs J I know it was red but I thought it looked better in pink" doesn't always go down too well.
As for the smell I'd add a suitable amount of clensan to the wash procedure and make sure it's bone dry before taking back.