Outdoor trash bins with flaps are better at keeping the waste contained, even controlling smells to a certain degree. However, these receptacles are also more prone to getting broken or needing to be cleaned, since the flap comes into constant contact with the waste.
Vanilla Essence: Pour several drops of vanilla essence on a couple of cotton wools. Toss the cotton wools inside the confined spaces nearest your trash can. Leave them for several days and you will notice that the area smells nice, or at least smells nicer.