Gouch. Fair reason to feel anxious, an unstable approach should be recognised well before the flare and certainly before touch down actually back at at least 500ft agl. Certainly any experienced pilot travelling as a passenger can make a fairly accurate judgement how stable an approach is if he is familiar with landmarks at a particular airport and is in a position to see the fixed distance markings disappear beneath the aircraft for many seconds before the first touch down prior to a bounce back into the air, normally caused from excess speed. Accurate speed and slope is vitally important on any jet and a go around must be the decision on any approach that is unstable below 500ft.