What Not to Buy Second-Hand (and Why)

Do not buy second-hand where the item's safety depends on a history you cannot inspect. Child car seats and cycle or motorcycle helmets top the list: a crash you cannot see can compromise the protection you cannot test. Add hygiene-critical items, mattresses with unknown histories, worn running shoes shaped to another runner's feet, and electronics locked to a previous owner's accounts. In each case the discount is real and the risk is also real, and the risk wins.

This is the companion to what to buy second-hand without worry. The two lists share one principle, explained in checking goods before you pay: buy used when condition can be verified, buy new when it cannot and the failure would matter.

Helmets protect by deforming in a crash, which means a helmet that has done its job once may look perfect and protect poorly. Car seats carry the same problem plus expiry dates on their materials and a recall history you would need to trace. Neither can be cleared by inspection, however careful. Buy both new, from a seller who can register the product and honour its warranty, and treat the full price as the cost of certainty, because that is exactly what it is.

The same reasoning covers climbing gear, life jackets and other load-bearing or life-supporting kit where failure is not an inconvenience. For these, second-hand is a reasonable source only inside expert communities with inspection norms and traceable histories, and even there, beginners belong in the new market until they can judge condition themselves. This guide's line is the household one: if a failure could injure, and the past is invisible, buy new.

Some items sit too close to the body, or absorb too much of a previous life, to reset with cleaning. Mattresses and upholstered bedding are the standard entries: they accumulate years of dust, moisture and worse, and professional cleaning rarely restores them to a state you can verify. Underwear, swimwear and similar garments are a plain no. Earphones and earbuds sit in a grey zone many households resolve with new tips and a thorough clean, or by buying new.

Makeup, opened toiletries and anything applied to skin or taken by mouth should not change hands used, however unopened they appear. The savings on such items are small in money and the exposure is not worth pricing. Notice the pattern across this whole section: the no-list grows where cleaning cannot be verified and contact is intimate. Your household can draw its own line with that rule in hand.

Running shoes are the classic false economy. Their cushioning compresses and moulds to the first owner's stride, so a cheap used pair can cost your knees more than a mid-priced new pair fitted to your feet. The same logic catches non-stick pans with failing coatings, knives ground down to poor geometry, tyres with unknown age and wear, and batteries of every kind sold loose, where the remaining life is the product and nobody can show it to you.

Distinguish worn-out from merely used. A cast iron pan is improved by its first owner; a non-stick pan is consumed by them. The question to ask of any candidate: does use consume this item, or merely season it? Consumable-by-use items belong on the new list unless the remaining life is demonstrably long and the price reflects it, which in practice is rare enough to treat as a no.

Modern electronics add a failure the old lists never had: the item works perfectly and still will not serve you. Phones, tablets, smart devices and game accounts can be tied to a previous owner's credentials, activation locks or subscriptions, leaving the buyer with hardware they cannot fully use or update. Where you do buy used electronics, buy through channels with returns and a reset you perform before money finally settles, and check battery health and update support, because a device the maker no longer updates is ageing faster than its case suggests.

Software licences, warranties and guarantees sit in the same drawer. Many do not transfer, or transfer only with paperwork the seller may not have. Price a used item as if its warranty were zero unless the transfer terms are in your hand, and let that honest pricing decide. The parts and manuals guide covers the happier side of this coin: buying used items whose makers publish parts and documentation is how longevity stays possible.

Keep your no-list short, written and reasoned, so it survives contact with a tempting listing. Every entry should carry its why in a few words: invisible crash history, cannot be cleaned verifiably, consumed by use, locked to another account. A list with reasons persuades; a list without them just feels like fussiness, and fussiness loses arguments with bargains.

Everything not on the no-list returns to the yes habit: check it properly and buy it used with a clear conscience. The point of a firm no-list is not caution for its own sake. It is what makes the rest of the second-hand market worry-free.