If reading that made you cringe, welcome to the world I'm going to be entering soon. One of the products here is a Linux based product, and was not originally developed by my company but was bought out by them. Well, I learned from my guys pretty early on why every freaking release breaks something. The reason is straight up lack of QA. The product has its code written for new releases. Then, a script is run against the code to check for typographical errors in the code. Lastly, it's released into the wild. The customers are straight up used as guinea pigs. Inevitably, the new version is released, and a ton of people upgrade, but because it was never actually run and tested for performance issues, etc., we get flooded with calls, after already being backed up from the previous release two to three week earlier.
Also, there is virtually zero documentation, there are a ton of different components and each has a ton of its own, unique issues. When Tier III gets involved, they will often fix it but they NEVER put notes in as to what they did or how they did it. So if I had a case, I can stay the communication owner so that when it gets closed or updated, I get notified. I haven't supported this product yet, but this is what I'm training for right now. Still, it blows my mind that a company can not QA a product at all! Especially one of this size and magnitude...fun fun...