Sign on range hood light switch says "incandescent or resistive 120V AC Only"; does this mean no CFL or LED?
CFL and LED bulbs contain circuitry that make them appear relatively resistive even though they contain inductive and capacitive elements. The warning is mostly against highly inductive loads since they can result in excessive amounts of current flowing through the circuit when the switch is opened.

But regardless, you should only ever use dimmable bulbs in a dimmer circuit, even if you will never use it at anything other than full on or full off; non-dimmable CFL and LED bulbs may not react well to the transient waveform while switching between them, and even "all the way on" can still have some undesired distortion.