Ok first off to clean the unit............Make sure it's empty with no dishes turn the unit on wait till it fills up with hot water and starts to splash around inside then open the door and add 1 1/2 Cups of bleach and let it cycle all the way through....if there's still smell try it a second time.....As far as your leak goes the most common problems with leaks are generally because the unit isn't level right to left and front to back or the door wipe on the bottom of the door is misaligned or cracked or missing. Also another factor is all your spray arms must be free of debris and have no food or items in them and should be spraying freely. Check to make sure you have no food particles in them and turn the unit on and open the door quick when it's running and make sure all 3 spray arms are moving freely if one is jammed it will spray straight at the door and cause it to leak.....another factor is check under your float switch for food debris that is really common for food to get stuck up in there and cause this issue also....should just pop straight up and out and clean under it and the housing it sits on........the door gasket going around the unit as you have picture is very rarely the issue ever its only a problem if it's badly worn and one of your spray arms are stuck and spraying straight at the door. I give it a 99% guarantee that if you check all the things i listed above you'll find one or more that's causing your problem. Check under the unit as well make sure it's not leaking from the gasket also but i'm assuming you're having a front door area leak.

First off this unit is one of the cheapest ones on the market in design and performance. What air gap are you talking about? There's no such part named that and if your refering to the door it's normal it's not a perfect seal no dishwashers are. And sure there could be moisture in it for weeks dishwashers always have water inside the unit you don't see in the base of the unit depending on if they have a drain hose that doesn't have a backflow flap. Also another problem you may have is unless your drain hose goes to an aerator the drain hose has to go above the bottom of the sink for draining otherwise the sink water will backflow into the unit without an flap type drain hose but that's an installation issue not a dishwasher issue.