None. That's why Jesus also said, "let he who is without sin, cast the first stone," when they brought the adulterous wife to him.
He knew that probably every man there, had looked at her with lust, yet here they all were ready to stone her.
Sure, blind men aren't looking at the girl across the room, but they have their own ways of lusting after strangers. Look at Ray Charles.
In Jesus' time, men were usually married by age 12 or 13, so they really were being unfaithful to their wives if they had sex with a new woman.