I love using things until they die. Sometimes I use them even after they've lost all ability for their original purpose, like using old bath towels for bath/kitchen mats. I do enjoy scouring the second-hand Facebook page to see if I can snag any items I need at a primo price, as well as appreciate the second-hand buy/sell/trading community for decreasing rubbish in their respective areas. I'm also quite keen on the fact that I can get deals like a lightly used, fully-functioning toaster oven for $6usd just because someone else is moving and doesn't feel like taking their toaster.
There are a few things I won't buy used, though: mattresses/bedding, undergarments, personal hygiene/anything used in the bathroom, and shoes. For the purposes of this blog, I will focus only on the shoes.
Shoes should be fitted to your feet. YOUR feet. Not anyone else's. Your feet are the foundation for the rest of your body. So I guess you could compare it to housing: you wouldn't use the same foundation for different houses, and you wouldn't use a pre-existing foundation meant for another house for your own. Or even dental retainers. If you've ever been so lucky to have had the pleasure of wearing these things, you'll know the feeling you get in your entire head and neck when you find your old retainer and see if it still fits.
Think about how different your feet are compared to your friend/spouse/parents/siblings'. Maybe you have Morton's Toe, where the second toe is the longest. Maybe you have wider feet. Or a lower arch. Or narrower heels. Squeezing your feet into something that doesn't fit is definitely not a good idea. Anyone who's bought shoes for looks rather than comfort knows that first handedly. The inside of your shoe should make your feet all nice 'n snuggly, but without any pressure squeezing it. There should be wiggle room in pretty much all directions for your toes, including sideways. Your heel should be comfortably cradled, but not braced. And please, please, please....toss the arch support. If you have a higher arch or fallen arch, please see a professional about how to correct it so that your feet regain their strength to support that arch correctly, versus using a brace for every piece of footwear you own for the rest of your life! Just like the rest of your muscles in your body, your feet can learn/re-learn things and get stronger!
Now think about how you walk. Maybe you haven't thought of that before. Some people supinate (walk more on the outside edges of their feet). Some people pronate (walk more on the big toe). Some people drag their heels, some people stomp with their heels. All of these are reasons why your shoe will wear differently on the outside (and the inside) than someone else with the exact same shoe. Ever watch "Big Bang Theory"? Sheldon's butt is already grooved into his seat on the couch, because that's "his spot." That's how your shoes are. And when you wear someone else's shoe, it's like sitting in someone else's "spot." Feels weird, but you can get used to it eventually. But the thing about getting used to it and grooving over someone else's groove is that the old groove is still there. Your groove just adds to it. So there's no support where you need it. Just a big hole where both you and the other guy can both fit.
The reason why cars need to get their tires rotated is to prevent the type of biased wear of being on one part of the car, much like our shoes, being on one foot of our body. But we can't really rotate our left shoe with our right. So we need to get new shoes. And if we use shoes that someone else has already grooved their Morton's Toe or bunions into, then we lose all the support that they already used up. Like popping bubbles on bubble wrap. You can't re-fill those popped bubbles. Just get a new sheet.
Now, you may just make the argument of "hey, what if I just get new inserts?" My response to that is to look on the bottom of that shoe. Does it show any signs of wear and tear? If the answer to that is even minutely "yes," then it's kind of like driving with your wheels out of alignment. And if you don't get them aligned (aka, get new shoes that fit your habits of walking), then you will hurt your body by trying to adapt to those misaligned shoes.
Shoes are supposed to last about 6ish months (if you wear them regularly). If you see wear on the bottom to where you don't see the treads anymore (more car/tire analogies!), then you need new ones. It's like not rotating your tires. Whatever bad habits you have for walking will be exacerbated and worsened by the wear.
One last scenario: If you have recently corrected/changed your way of walking, or the shape of your arches, etc, you also need to get new shoes. Otherwise you're just going to be fighting your shoes to maintain your old ways...and your shoes will probably win. It'd kind of be like fixing the alignment, but not getting your tires rotated since pre-alignment.
Second-hand clothing is fine, but treat yourself when it comes to shoes. Go for comfort first, not for looks. Make sure they fit to your feet well. Let your toes have the capability of wiggling around and not getting bound into shoe-shaped feet. Make your shoes fit your feet, not the other way around. Your feet are the foundation to your body. If your feet are not healthy, the rest of you will be paying for it, too.
I realize I didn't talk about the thickness/hardness of the soles....that's an entirely different topic. I covered some of it in my earlier blogpost about the Vibram FiveFingers, but it's more about transitioning into minimalist shoes rather than the actual topic of thickness/hardness of the soles.
Anyway, even though your feet are on the bottom of your human totem pole, realize that they are what keeps you standing. If they hurt, I guarantee more of you will hurt. Treat those things with care. Chinese foot-binding is out of practice for a reason, as well as wearing another kid's retainers. Get your own. Make sure they fit. Your feet (and hips, and back, and neck) will thank you.