Infant/baby car seats
Absolutely, you should only buy them new.
We felt comfortable with a hand-me down from a trusted friend. As long as it's not expired and hasn't been in an accident, I'm OK.
A motorcycle helmet, I can understand. The protective foam liner gets more brittle with age and you can't test it without also damaging it. Manufacturers recommend replacing them every five years but I consider that a very conservative estimate considering the source. I will probably wear mine for around 10 years, give or take, before replacing it. The helmet may even still be perfectly good at that point, but I assume that improvements in helmet design over the course of a decade will be worth the upgrade alone.
I am perfectly okay with throwing away a child car seat that's been in an accident but car seat expiration dates are total and utter bullshit. The seats have a very simple job: hold a baby to the seat. This is not a difficult engineering task. They don't make them out of anything that deteriorates significantly with time and age. Can you imagine if they did? There would have been about a thousand and one class-action lawsuits along with several swift, overly-broad, and non-appealable actions from the CPSC by now.
Car seats are essentially a one or two-piece strong plastic shell, seat belt straps, and some padding for comfort. That's it. The seat belt webbing doesn't go bad, the padding doesn't matter for safety purposes, and the plastic shells will haunt our landfills for millions of years.
When our kids were babies, we had two car seats that were acquired used. (One we bought from craigslist, one was given to us for free.) They were similar designs and made the by same company. One was about five years old, the other about ten. Oddly enough, the ten year-old seat was better made and stronger than the newer one. I know this because I stripped both of them down, cleaned them, and inspected them for signs of damage and weakness. I found none and happily declared both of them fit for protecting the most important things in my life.
Now that we're done making babies, I have to throw the perfectly-working seats away because it's illegal to sell child seats that have been recalled. Now, before you say, "wait, that's a good thing", I have to point out that nothing about these seats is dangerous in any way. If that were the case, I would not have put my babies in them. The real story is: one of the seats had an optional rain cover or something that could pinch a baby's fingers if said baby had fingers in the mechanism while an unobservant adult retracted the cover. First, I don't see this being a recall issue to begin with and second, my seat doesn't have a rain cover. As for the other seat, there is nothing wrong it either, but it was originally sold with a stroller that had a defective wheel or something. We never had the stroller, but the seat is considered recalled as well because it was sold with it and has the same model number.
Sorry for the rant, I just get rather worked up about the lack of common sense in general when it comes to child safety products.
