in some spray ie carb spray; residue (a little greasy is requried/left behind when there is moving parts)
contact cleaner as the name suggest is used for sensors / electronic boards / diodes.
you can purchase the CRC MAf sensor cleaner (red can) as attached image & later compare with the CRC contact cleaner (blue). just spray a little on your hand. it should leave no residue & it will quickly evaporate (alcohol/methanol base i think).
because can is pressurized, hence when directed to the sensor (dont touch but 4"-6" away), it blows off dirts or contaminants that may have built over a period of time. more so with cars with open pods filters. pressurized cans do have a plastic hose.
though maf sensors will also eventually comes with a product shelf life. esp for tuners readings may deteriorate after some years (even with care cleaning). these were debated in some forums before.
if one cant afford to change maf sensors every 6 months (instead use contact/maf sensor cleaner), then change a new one 3-6years later.