There's also the best kind of hurt: outdated, insecure firmware that gets delivered to users who aren't aware of it, can't inspect it anyway, and even if they could, they can't do anything about it because the firmware is signed and you can't load your own.
This particular type of hurt is why I like GPLv3.
Especially painful hacks are graphics and WiFi drivers.
The trouble of course is that people do not go to complain to, say, Nvidia that their GPU does not work, but to the distribution maintainers or kernel developers who have no control over the driver.