The ever-growing market for used and refurbished tech and gadgets can indeed be a great way to save money.

However, there can be some pitfalls if you aren’t careful, as you might be handing over your hard-earned cash for a defective product. There are also a few health and hygiene concerns that you should be aware of before making the splurge.

Here are five tech items that you should never buy used. If you still feel that you can’t live without them, save up and spend a little more to guard yourself from future troubles.

Up first are personal hygiene tech products like electric toothbrushes, hair trimmers and electric razors. Obviously, there are hygiene concerns abound here. Sure, you may be able to replace that brush head with a new one, but that toothbrush handle still has gone through the warzone of that person’s daily toothbrushing routine. No matter how cheap these products are, it’s best to just stay away.

In at No. 2 are OLED TVs. These panels are arguably the best on the planet, and therefore don’t come cheap. Many of the newer models can be priced in the $2K to $3K range, so there will be people out there searching for awesome deals to take advantage of. The thing about OLEDs is that they can be susceptible to image retention and burn-in, in which the former can be a signal of the forthcoming permanence of the latter. Keep in mind that these panels do have finite lifespans, so it is recommended to save up a bit more and buy a brand-new one.

Next up are earbuds and headphones. Audio products like AirPods and Pixel Buds must be used by sticking them in your ears, so no matter how well you can clean them, there will always be issues concerning proper hygiene. Even over-the-ear headphones can’t be 100-percent germ-free, as the earpads can soak up people’s oil and sweat.

Wearables like fitness bands and smartwatches are other products that you should pass on. There are certainly plenty of amazing deals out there for them, but you will never know how much abuse they have endured. Sure, it may look fine on the outside, but the internals could be an entirely different story. Also keep in mind that the battery that comes with the wearable could be on its last legs.

Lastly, it’s always a good idea not to purchase a used portable hard drive. They are relatively reasonably priced anyway, so why risk getting a problematic device to save $20 or $30? If you do purchase one, however, make sure that the previous owner thoroughly erased the drive, as you probably don’t want to come across their personal information later on.

Ethen Kim Lieser is a Science and Tech Editor who has held posts at Google, The Korea Herald, Lincoln Journal Star, AsianWeek and Arirang TV. He currently resides in Minneapolis.