Left ambiguous, but potentially dark.

She was looking great. That dress was perfect, short, sexy, showing off every sexy curve she had, and she had so many sexy curves. Her body was so nice, so hot, and when she walked those legs and that ass moved in a way that would get any man hard as a rock.

Marty wouldn't have to worry about getting hard from her anymore. It was a bit difficult to when you don't have a dick anymore! He smiled as he walked away from his secret lab, feeling those legs and that sexy ass move, feeling the brush of the nylon on his legs and the satin of his dress. Her head wasn't looking so hot now, but the rest of her was still enough to get any man going and that was exactly what Marty was looking for!