Second-hand electronics have measurable condition and you should insist on the measurements. Battery health percentage on a phone, charge cycles on a laptop, shutter count on a camera body, flight hours and battery cycles on a drone. A seller who has the device in front of them can read all four out in under a minute.

Humidity is the local villain. Salt air corrodes charging ports and camera contacts, and a device that has lived in an open-air villa near the beach ages differently from one that has lived in air conditioning. Ask where it has been kept.

Check the ownership trail too. Ask for the original purchase receipt or box, confirm the device is not locked to another account, and for phones verify the IMEI is registered for use in Indonesia — an unregistered imported handset loses local network access.