Some things are worthless, but not all used items are worthless. People buy Used things all the time, and that includes dishes and clothes. Go to the Salvation Army warehouse, you'll see your argument doesn't hold any ground at all.
You're drawing an illogical conclusion based on something that isn't true. The game doesn't mark a "Paintbrush" as a "Paintbrush that was found at the bottom of a river". as far as the game knows, it's just a "Paintbrush" the very same one the vendor may or may not sell.
Well of course. You're absolutely right on two counts. First, not all used things are worthless. I have been advocating for the occasional useless item, not that all clutter be worthless. I hate to make you back up even further, but my original post or two in this thread were all about how some things of value should be scattered in with the clutter, more like hammers or the cloth bolts. Of course we agree then, that some used things have value and that the player should be able to pick through. We also need to go ahead and agree that some things are NOT valuable, and that it's a nice feature of the game to be able to recognize that and throw a few clutterjunk things in the mix.
You also point out that it's possible to be selling something that's new. Yes and no. If you buy a brush from a vendor and turn around to try and sell it again, sorry, but you're going to lose money on that. It really isn't new, unless you happen to be in the paintbrush business and you bought it from a supplier. Problem is, game economies are not complex enough to introduce supply, demand, vendors, retail, and wholesale. That's a little too ambitious for now.
So as a compromise, we just assume that you are not a merchant. Thus anything you own, whether you just bought it or not, is used. If you buy a brand new paintbrush for 1 gold and try to sell it, you will get less than 1 gold because you are selling it second-hand. The only thing less than 1 is 0.
So some items, even if they ARE considered new, are just plain worthless in your hands.
Be mindful what you think my conclusion is, because I don't think you had the whole picture of my argument in mind.