Depends on whether we are talking about 'used' or 'vintage'. And how much are you saving. I have bought two non-new bags -- one is a large quilted lambskin Chanel weekend bag and the other is a Lambertson-Truex in a really hard to find color. I will only do that if I can touch and feel them (no eBay) and they are spotless.
I would buy vintage or secondhand if the bag was clean. Some bags are impossible to get, otherwise! Also, some older styles are better than modern styles.
I wouldn't buy anything dirty or damaged, though.
Most of my bags are new, but I have a couple of pre-owned ones. My Balenciaga was pre-owned; the woman I bought it from used it only once. It's in perfect condition, not a sign of wear on it, and I got it at a great price. My LV Speedy 25 was also pre-owned, and I love how the handles already have a nice, dark patina on them. I also got a great deal on that bag. It just depends... if I see a bag that has been owned before, but is in great condition and is selling for a good price, I'll go for it.
i don't have a problem buying a preowned bag. my balenciaga was preowned, used maybe once or twice, and i didn't have a choice because they were sold out everywhere in the color i had my heart set on. i also purchased a vintage speedy on ebay because i wanted one that had already patina-ed and i don't have the patience to do my own.
I have a used LV and it looks great. That's the thing about these high-end handbags, when cared for, they do last for decades. They shouldn't just fall apart like your average cheap bag might. MY LV is ten years old and looks great, and is as sturdy as it ever was. I have no problem with a used bag as long as it is clean and in good condition, and is made by a brand that I know has a reputation for longevity and excellence.
I prefer new bags and I've got some on eBay that are brand new with tags so that's a steal for me. If it's a bag I really want, it has to be in near new or excellent condition for me to buy it or else I'd just rather pay the full price or buy somewhere else that has it in a better condition. If it's a pricier bag like LV, I won't mind that it has been used for a while as long as everything is clean. I tend to avoid those iwth ink stains or water spots or spills inside the bag.