To read code is to understand it. It has little to do with style but more to do with program structure and abstraction layers. I've maintained a PHP codebase with some of the worst code I've ever seen. For Example:
1. A function with a few thousand lines of code, accepting dozens of parameter. The body is made up of some nested switch-case and if-else.
2. Instead of using constructors, every class has a static method that does nothing but initialize itself.
3. A class which queries DB and generate HTML, with nearly a hundred public variable. A few levels of sub classes with functions to update those variables.
When a piece of code is not obvious in what it's doing, I'll call it unreadable. In some cases this is acceptable, for example in some clever algorithm (https://en.wikipedia.org/wiki/Fast_inverse_square_root), but it is still what it is, unreadable.
1. A function with a few thousand lines of code, accepting dozens of parameter. The body is made up of some nested switch-case and if-else.
2. Instead of using constructors, every class has a static method that does nothing but initialize itself.
3. A class which queries DB and generate HTML, with nearly a hundred public variable. A few levels of sub classes with functions to update those variables.
When a piece of code is not obvious in what it's doing, I'll call it unreadable. In some cases this is acceptable, for example in some clever algorithm (https://en.wikipedia.org/wiki/Fast_inverse_square_root), but it is still what it is, unreadable.