You can only reliably smell hydrogen sulfide in very LOW concentrations, so the fact that you don't smell it only means that if there's any there, it's not at low concentrations. Could be none there, or there could be a lot. Some people say it smells like flowers, or sickly sweet, at medium-high concentrations, but as all the safety docs say, don't count on your sense of smell at all when it comes to hydrogen sulfide.