How to test used hardware before you buy
A checklist for meeting a seller with fifteen minutes and a phone. Every check here runs in a browser, so you need nothing installed.
Buying used peripherals is good value, right up until you get home with a mouse that double clicks. Everything worth checking can be checked in a browser, which means you can do it at the meeting on a phone.
Before you go
Bookmark the tests you need. There is no download and no account, so you can open them on the seller’s machine if yours is not to hand, though taking your own laptop is better.
Charge your phone. Take a USB-C and a USB-A cable, since half of what you test will not come with one.
Mouse: two minutes
Click chatter is the thing to check. It is how most mice die and it is invisible until it starts. Click the left button 30 to 50 times at a normal pace and watch for any double registration. A healthy mouse records none.
Optical switches cannot chatter at all, so if the model uses them, that particular risk is off the table and you can spend the time elsewhere.
Then the scroll wheel. Scroll slowly in both directions. A wheel that jumps backwards has a dirty or failing encoder, which is repairable but is a bargaining point.
Then every button, including the thumb buttons, which are frequently remapped and occasionally dead.
Check the cable by flexing it gently near the mouse body while clicking. Intermittent dropouts that track the movement mean a failing strain relief.
Keyboard: two minutes
Press every key and confirm each one registers. This is the whole test, and it catches the only fault that really matters on a used board.
Hold several keys at once and note the rollover peak, which tells you whether the board does what you need for gaming.
Look for keys that register when you are not touching them, which means a stuck switch. And check the board for obvious liquid damage: sticky keys, discoloured plate, corrosion around the connector.
Controller: two minutes
Stick drift is the check. Put the controller down, hands off, and measure both sticks at rest for a few seconds. Anything above about 0.10 will move your character in game.
Press every button, including both stick clicks and the guide button, and pull both triggers through their full travel to confirm they reach maximum.
Do this wired if possible. Bluetooth adds variables you do not want while evaluating someone else’s hardware.
Monitor: five minutes
Dead pixels need a full screen colour cycle in a reasonably dark spot. Clean the screen first, because dust looks identical to a dead pixel and you will not want to argue about it afterwards.
Backlight bleed shows on a black screen. Some is normal on edge lit panels; a lot is a reason to walk away or negotiate.
Refresh rate should match what the seller claims. A monitor sold as 144Hz that only offers 60Hz may be mis-described, or may just need the setting changed, and it is worth knowing which.
Check the physical ports too, since a dead HDMI input on an otherwise fine monitor is easy to miss and expensive to discover.
Headset, microphone and webcam: three minutes
Check the microphone level responds to speech, then check each speaker channel separately. One dead channel is the most common headset fault and takes ten seconds to find.
On a webcam, confirm the resolution it actually delivers rather than the one on the box, and check the picture is sharp at a normal sitting distance.
Flex every cable near its connectors while watching for dropouts.
What the tests cannot tell you
A browser test finds faults that exist now. It cannot find a switch that is worn but not yet chattering, a battery that has lost most of its capacity, or a thermal problem that needs twenty minutes of load to appear.
So weight the price accordingly for anything heavily used, and ask how old it is. For mechanical switches in particular, age is a reasonable proxy for how much life is left, since chatter typically appears somewhere between two and four years of regular use.
Common questions
Can I really test this stuff at a meetup?
Yes, for anything with a USB or Bluetooth connection and a browser to plug it into. A phone handles controllers, headsets and screens. A laptop is better because it covers keyboards and mice too. Take one if you can.
What if the seller will not let me test?
Treat that as the answer. Testing takes five minutes, costs the seller nothing, and a genuine seller with working hardware has no reason to refuse. Refusal on a peripheral is a strong signal.
Is buying used mice and keyboards a bad idea?
Not at all, but check the specific things that wear. On a mouse that means click chatter and the scroll encoder. On a keyboard it means every key and the rollover. Both are the parts that fail, and both are testable in under two minutes.
What about buying online where I cannot test?
Test the moment it arrives, before the return window closes. That window is worth more than any warranty, because it needs no defect threshold and no argument. Run the checks the same day.
What cannot be checked this way?
Anything that only appears over time: a switch that is worn but not yet chattering, a battery that holds charge for an hour instead of eight, thermal problems that need twenty minutes of load. A browser test catches present faults, not imminent ones.