It's unclear what is going on with the cracked screens. You can read what folk post in many forums but I will not enter into a discussion with folk about this because they have an issue and I can't help them. We see the posts but it's unclear what the cause is. If you say it's impact they will tell you they didn't, if it's a side effect of mass manufacturing then the makers are silent.
For now here's what I know. If it's a star shape, it's impact. If its some long single crack, the maker might replace it as a defect.
As you can find out how plasma and LCD screens differ, I won't detail that here. But imaging those that stretch their budget with a many thousand buck set and then this happens and there is no warranty. They will explode and lash out at anyone that discusses the subject.
I can understand that.
Light bulbs you shouldn't buy
There are plenty of dimmable LED light bulbs, but make sure you don't buy the ones that flicker when you dial them down.