There's a sense it which it isn't your responsibility to figure that out. If they never check, you avoid annoyance. If they do check (A/B test, eyeballing it, w

There's a sense it which it isn't your responsibility to figure that out. If they never check, you avoid annoyance. If they do check (A/B test, eyeballing it, whatever), they'll see. If they're unwilling to turn it off no matter what then they're kind of terrible, and probably should lose lots of traffic.