Yeah, you can quite easily leave the door ajar, it looks fine.
On the other hand, if you're doing fairly regular washes it's not a big deal, I've never had any problems with smelly washing machines.
Problems are :
1) Not washing hot enough - You need to run the occasional >40C wash i.e. 60 or 90C wash with towels now and again.
2) Not using sufficient detergent - machine doesn't clean and you may also cause limescale issues.
3) Hard water - lime scale deposits provide a breeding ground for goo.
4) Poor quality detergent. None of the major brands, and even the better supermarket brands will be any problem. However, if you're using cheapy and nasty brands, there are some issues in the long term as they leave deposits.
In general, if you're running cotton washes with a decent rinse cycle, your machine shouldn't get smelly.
The aqualtis, like many new machines, has a rubber bellows seal designed not to accumulate water i.e. there are drain channels in it.
Also, it's worth wiping the door seal out with a cloth and perhaps a little antibacterial cleaner like dettol (formerly detox) once in a while.