It's not that, it's that they use inconsistent and non-standard formatting.

For example, in JavaScript, there is always a space before a function's opening curly bracket. This is pretty much a global standard, and it's rare to see code that doesn't follow this rule.

However, I'll occasionally see code on Stack Overflow that randomly excludes these spaces. It honestly makes it so much harder to read, and I'm less willing to put in the effort to help them, because they didn't even go to the effort of properly formatting their code. Inconsistent indentation especially kills me because it makes code impossible to read.