depends - sometimes someone will say 'I did 40 in a 30mph zone, what will happen' and along with one or two useful answers, if they're lucky, will come 20 accusing the OP of being a menace to society and hoping they rot in jail. That sort of thing would dissuade any questioner from using the site.
But I've no problem with someone trying to catch the attention of the OP, or another contributor, for some off-topic purpose; it's often the only way of doing so when you know they're posting. I've done it myself. I'd usually apologise to the OP while doing it, though.