In slang, if someone describes something as "grody," what do they mean?

Initially written in the mid-1960s as “groaty,” this term basically describes something that is slovenly, dirty, or super gross. If something is truly terrible, you might describe it as grody to the max. As the Los Angeles Times wrote in 1982, “Grody is used to describe a disgusting object. Moon Zappa calls her toenails ‘Grody to the max,’ which means disgusting beyond belief.”

Source: Mental Floss