Williams, who plays for Paris club Racing 92, was charged by police for allegedly buying cocaine last week and has been suspended by the club.
Read, who played with Williams in the national side, says it's a wake call to all past and present players of the standards expected of them.
"It's a reminder if you've been an All Black there's a brand or standard that needs to be kept," Read said.
"The All Blacks always want to keep standards high, it's important that you respect that.
"But if you make a mistake it's out there. It's disappointing."