Certain items you should only consider buying new. Items like mattresses. However, a pre owned bed, a reconditioned fridges or even a second hand dining room table might make more sense for you to consider. Especially when you have all relevant facts (how old it is, how much use it has gone through etc) to make your decision. Not only are these items going to be cheaper, in many cases they have very little use and will last as long as new items will last you.
Additionally, these items will cost much less than brand new. Items like wardrobes, sofas, cupboards and other furniture can also be purchased used. If you decide to buy items which are second hand, the most important factor to consider is buying from a "certified" seller. Not only do they warrant all items they sell, they fully inspect, maintain, and work on the equipment themselves, before selling to you. All refurbished or pre owned then the products will be checked to make sure they are working correctly.
It is possible to find great deals on homeware when buying used but make sure the seller is certified and you have done your research about the product you will be buying. If possible try and get a warranty. These are the best ways to ensure a long lifespan for these items, as well as your safety when putting these items to use in your home.