Code review is part of my job, and you cannot know the crap I’ve seen. Like someone pointed out, it’s also sometimes the crap I’ve written 🙂 In all cases, however, it’s because some developers do not have deep knowledge of how things work: most learnt something (in university or from a senior developer) years ago and don’t challenge this information regularly though technology evolve. Others just google the problem at hand and copy-paste the first snippet in their