I come from a long line of know-it-alls and it's been a life-long effort to control my know-it-all-ism, but in recent years I've had some success in that I do not give unsolicited advice unless it's an issue of safety. So if I notice that you've got your helmet on backwards or that your jacket is about to get sucked into your wheel, I will tell you. If I notice that your saddle is too low, I won't unless you ask.