This question is what brought this issue to mind for me:
This is apparently an AD&D question, but it addresses a rules element that exists (at least) in both AD&D and D&D4e. The real issue I have here, is that the only place the system/version was specified, is in the tags for the question.
After reading the title and question, I began writing a response based on the D&D4e rule, having practically no knowledge myself of AD&D at all, let alone that this rules element also existed in that version.
It wasn't until I was half-way through writing the post, that I noticed the tags referencing AD&D and realized that my answer may be very inappropriate depending on the differences between the versions of that rules element.
To prevent similar confusions in the future, should we enforce via mention in the FAQ and/or question editing, a specification of system/version in the title and/or text of the questions?