I've been getting almost all of my clothes at a 2nd hand shop since I was in high school...I'm 37 now.
Here are my reasons.
1. style- there is a vastly larger selection of styles (or can invent your own) when going to 2nd hand shops. You can get clothes from almost every decade- especially the fancier vintage clothing shops. Thumbing through current magazines of stores that sell only new clothing --the style/look isn't always what I'm looking for...which leads me to my 2nd point.
2. originality- I don't want to be wearing the same shirt -thats massed produced by the large clothing chains- that hundreds of other men are wearing. I want to wear an outfit -that friends or even strangers will say- 'hey thats a cool shirt ..or jacket..where did you get it?"
3. price- being always aware of keeping my spending low -I can't reason to buy one shirt thats brand new for say $35 (or more) when I can buy 3-4 used shirts for the same price-- and they are in great condition as well! Not like I'm buying damaged clothing just for the sake to save a few dollars..most times the shirt looks new and you wouldn't be able to tell other than the fact it didn't some in any fancy packaging.
4. makes me money- going to a used clothing store you just never know what you'll be leaving with--- sometimes I'll go to buy clothes only to resell on online auction websites for 3-4 times the price and make a profit
I think its fun and unpredictable... of course there are some items I buy new...pajamas, underwear, bathing suits.....but the rest is all used clothing.
As far as the bad luck superstition, I can see what you mean...but I look at it like this.... in life you make your own luck, the decisions you make ,the actions you do will dictate if its good luck or bad luck. An item of clothing has no power over you or your future --its a piece of cloth and no matter who wore it prior has no correlation to your life. Thats how I see it anyways...