I worked an inbound just recently who only had 2 greens, believed to be a bulb fault (as it subsequently turned out to be). However, the crew accepted the offer of a low approach and go-around for a look from the ground. ATC, Airfield ops and the fire service all looked and all passed on that everything appeared normal. Of course there's no way of knowing about downlock or other problems, but the crew know that; it's just so we can point out when something is obviously wrong such as one gear leg not fully extended, nosewheel turned at 90 degrees to where it should be, wheel missing etc. Fortunately bulb faults are much more common than the other stuff!!!!!!!!!!!!!!!!!!!!