if it is not fairly even, you should get a discount. unfortunately the reality is, as I'm sure you know, even a rug folded up for an extended period of time showing a crease can be a difficult point to explain to a buyer. many want to buy the rug as it is expected, not wait.
The nature of a washed rug is inconsistency. Almost always with luster and herbal. Sometimes this comes out over time. If it's really bad, it often has to do with differences in pile height accentuating sheen in some places more than others, maybe a thinner wool used weaving can create significant discrepancies. If a rug was improperly rolled, or rolled loosely too soon after a wash this too can affect the sheen. Uneven concentration of chemicals added to the mix is just another variable. Especially if it's a lemon wash for luster the chemical absorption rate and reactivity can vary a lot.
From the looks of it, this rug was probably folded at one point, then rolled improperly after wash.