Dust can get into the sensor in a variety of crevices in the lens assembly, and the front of the lens is just one of them. Dust that gets in the front of the lens does not come into focus as much as the dust on the sensor, so products such as the AC Maxx Lens Armour filter which protects the front elements won’t really help in that sense, but it serves as good protection against smears and scratches to the front element.
Never put your camera in your pocket because of the dust and lint in there. Put it in a poach before placing it in a clean camera bag, and you should not have that much issues with the dust. Hope this helps!