To be fair, it's one of the things that goes with the turf
We can't fault people for wanting to get involved, but as you say when it derails the topic you have to be careful. I would only try a trick like this with someone I know wouldn't be discouraged by it; if one of the people who are generally quieter started a tangent I'd be more than happy to let them get on with it!
(Although personal opinion = // = theoretical debate *shudder* )
(Sivvus trolley collision in the fruit aisle led to a jam, Sun 9 Dec 2012, 16:43, Reply)