>> What is the likely device sensitivity of a thru-hole ceramic capacitor?
>> My general understanding is that passive devices are not ESD sensitive.
Many types of component can be damaged by ESD - including passives. Whether damage is likely to occur depends on the ESD withstand of the component and the strength of the ESD. (Taking an extreme example, lightning is a form of ESD!)
In the case of capacitors, damage can occur if the capacitor is charged up enough to exceed the dielectric breakdown voltage. This can occur if sufficient charge is dumped into the component in an ESD event. Low value low voltage types will require less charge to exceed the breakdown voltage and so it is normally these that might be susceptible to damage. Low value MOS capacitors may be particularly prone to damage.
Many higher value capacitors are reasonably rugged from an ESD view and can largely be considered not susceptible to ESD under ordinary circumstances - especially if the y have high breakdown voltage.
Some types of resistor, such as some film resistors, my also be susceptible to ESD damage.