I used to work for a company making high end communication equipment (I'm talking about core networks shit, not consumer), and one of their products code looked like someone opened a C book, did the typical printf( "hello world\n" ) example and continued from there to code the device. Disgusting. And not one single comment to spare. To make it better, that code never ran outside of simulation mode - they had a MANUAL TRANSLATION of that code to DSP assembly. Which means - you change a line of C - some human drones came and translated what you made into DSP assembly.
Later, I used to work for one of the major mobile phones manufacturers, doing some very focused platform work (Bluetooth support, etc.). The code of that thing was the most monstrous, disgusting, disorganized piece of shit I ever encountered. Hundreds of thousands of files, preprocessor programming ('#if 0' all around), no comments (or worse - not in a language I could understand). Piece of shit. I will never, ever buy a mobile phone from them, ever.
One time I refused a project after seeing the source code. It was the only time I did so. It was source code up to 15 years old, all developed by a single person who probably never saw a line of code outside his own. Those are the worst, as they never have a chance to understand what they're doing wrong.
Yes, I've seen my share of crap.