It ain't gonna happen.
I've hear lots of non pertinent on CVRs and rarely is it a problem.
I certainly would not trust a non-safety professional to decide which while protecting privacy.
The way to get at this a problem is the public release of non-pertinent conversation that does interfere with a flight. After the fact yes, but it still has the desired effect on other pilots who want to clean up their act.
I dare say that they are lots of pilots out there who have made an occasional transgression of no consequence, but who will now tend to cut their chatter short in critical times just to avoid an embarassment in the future (there but for the grace of God go I)