Locking/deleting questions

Totally random thought..
You know how advisors can either lock or delete questions
How do you choose.. Why do you lock some questions, and just delete questions all together on others??

Lock = there is value there before it got out of hand...delete = if the question, itself, breaks the rules.

So...if it's a good question, good answers, but then people get a bit too heated, we lock it to stop the bickering

Questions get locked and go up for review when we are not sure if they are violating the terms of use or not. It get's reviewed and if it does break them - it's deleted. It it's not - it's reopened.
Or sometimes it get's locked if the question had some good answers, but it turned into an argument.

The get deleted if they are in no doubt violating the terms of use.