It's just that their feet are not very functional. Aside from using them to perch, Hummers don't use their feet for much else. Unlike most other birds they do not use their legs to push off when entering into flight. Their sole means of propulsion is the awesome power of their wings. When in flight they flap their wings at a rate of 50 times per second, and as much as 200 times per second when in a power dive, which is a mating ritual practiced by male Hummers.
Hummingbirds can fly forward, backward, and they can hover.
They have also been known to fly upside down. Hummingbirds are quite relaxed around people because of their ability to hover and fly backwards. They know they can get away quicker than humans can react. They are curious creatures and will often hover right in front of your face studying you. Their diet is very high in sugar, consisting mainly of nectar and tree sap.