Well I dont know bout social workers but at the airport I work at no one was unable to work while they were waiting on the Disclosure being completed as if we were the companys would have had to pay as it was never a stipulation of employment before last year.
As for working abroad for Al Qaeda/eta/ira and being untraceable I think this is classified as period where you are untraceable and as far as I know rejected by the authority you are applying to?
I know this has happened to several people who have been offered jobs at the airport who were then told they could not start as they had done the whole 6 months around the world bit!
As for common sense checks where would that get us with the majority of aircrews?
Still have to deal with jumped up bus drivers with no regard for security procedures on the ground which are there for theirs and their passengers safety!!!!!!!