o Worked for large co; found several "Sev 1" bugs on a product was was proposed to be released soon. I was put on inventorying computers; product became one of the larges failures in company's history due to -- bugs.
o Same co, later: needed to make a code drop to another business. My job: To make sure that the code worked as expected, and could compile. (they got a "special" version of the code.) I told the PM that we shouldn't have the code on a given storage server -- it (the code) could accidentally be "compiled" causing problems. PM said that would not happen. A few days later, someone compiled the coded on the storage server. PM required that I had to find a way to 'fix it'. At the same time I looked into 'who' compiled the code: The same PM. (This PM was also was responsible for a lawsuit that cost the company millions... and was promoted.)
o Worked for a local utility. Was told that we were going to use a copy of "live customer data" for dev/testing. Objected, was told that "test" customer data could NEVER be visible to "real world". Two weeks into testing: Customer Service contact us -- customer billings were off. Sure enough: "test" was crossed over with "production". (My contract was suddenly "ended" shortly after I reported the security error - that was EXACTLY as I had predicted). About six months later, the state Attorney General was looking into the utility for using ... live customer data for testing.
o Worked for an aerospace co. Spend a week creating a detailed functional spec on a report needed by the business department. The developed report (delivered a month late) looked NOTHING like the spec. The totals didn't add up to anything, the columns were out of sequence, the colors were wild (not random -- just not anywhere near the spec.) Three days later, my contract suddenly ended.
o Worked for a company that managed big data. Found out that they had single point of failure ("fail-over"), and I had experience with fail-over situations. Was told that the data center could never be down for very long, and that this risk was minimal. About three months later, the data center suffered a catastrophic failure that took over a week to get minimal power restored. People involved with the failure were promoted.
So many, many, many more times: Like when development released product to production without consulting testing and caused customer data errors, like development removing all permissions on a SQL table to get their dev work done (when the permissions were re-applied, the code didn't work any more)
A good QA / Tester need to know all of the jobs: Development, PM, customer service and Testing to get the job done. Unfortunately QA never gets paid the level of knowledge that it has, the risk that it assumes, and - it's not unusual for bad management to (FREQUENTLY) have QA reporting to development; for bad management frequently blame the messenger. Interesting all the years that I've worked in QA -- I've never seen bad management get the blame.