I’d say it’s a toss up between PHP and Javascript.

PHP is awful and Javascript has a lot of bad points. In fact, it’s my opinion that it’s getting worse and worse because of modern “fashionable” coding styles. Oh, and node, don’t forget node. I’m not going to go into the problems that these languages have.

The main reasoning is that these are two of the most popular and easily-accessible languages around at the moment. They dominate the web, and have done for years, and the majority of programmers these days seem to be web developers.

So there’re a lot of crappy frameworks and libraries for both. People get frustrated trying to use easyThingFooer3000 in a professional environment and blame the language rather than the kid who made it in their bedroom.

You end up with frameworks which inherit the design decisions of the language: PHP frameworks with random ordering of parameters into (haystack, needle) vs (needle, haystack) for example, because nobody knows which convention to follow. So many libraries to do pretty much the same thing mean that your product ships with 30,000 lines of duplicated code you’re not even aware of. Is that bad? Meh. Debugging it is difficult, and it makes people hate the language.

Other reasons for hating these two in particular: the bandwagon effect. Yep. That old chestnut. It’s trendy to hate them.