Laughing at someone's code is like laughing at someone's painting or their novel or really any other creative endeavor. It's not ok period.
Hell, every now and then I stumble across some idiocy in the code base and think "LOL, whoever did it this way is an idiot". git blame. "OH, hahaha, it was me, what an idiot past me was, amirite guys?" Everyone on the team takes levity about mistakes very seriously ;) It's healthy.
Mocking condescension on the other hand is a different thing entirely.