Good Sims don't generally consider performing mean interactions on other Sims.
Good Sims will not have negative reactions to social interactions as often as other Sims.
Good Sims will boo other Sims who work as an Emperor of Evil, the top level of the Criminal career's Evil branch.
Good Sims have an easier time befriending Unicorns, and the relationship between the Good Sim and the Unicorn will decay slower.
Good Sims are sympathetic, and will appear genuinely concerned if another Sim is experiencing misfortune, rather than laugh at them. They also will be sorry for a Sim who has caught their partner cheating in front of them.
Good Sims will not be able to fight a burglar, even if they have Brave or Can Apprehend Burglar traits. Also, because Good Sims cannot initiate the "Fight!" interaction, the increased chance of winning fights from the Can Apprehend Burglar hidden trait has no effect. Good Sims still retain the increased chance of winning fights from having the Mean Spirited and/or Brave traits however. In bars, clubs, and lounges (except future lounges), they are still able to initiate brawl, like other Sims.
Strangely, Good Sims can have the Mean Spirited trait, which is considered equally mean to Evil trait
"Don't consider performing mean interactions" means actually having most mean interactions locked from the Good Sims, even if they also have the Mean Spirited trait. As a general rule, only mean interactions related to anger such as "Argue", "Accuse of..." or "Yell At" are available to Good Sims. Mean interactions that pose major changes to relationships like "Break Up" or "Ask to Just Be Friends" are still available to Good Sims as well.