Any grease or markings on the wheel when received are a normal part of the manufacturing process. The wheel is not polished prior to shipping.
Consider buying 2 because if one wore out the other may be right behind it!! (Speaking from experience:)
>>To avoid unnecessary returns please view ALL the photos especially any with measurements. Compare the measurements with your wheel, pay close attention to the measurement of the center of the wheel. This is where most people make a mistake. The inconvenience and extra costs of returns are avoidable with do diligence.