Originally Posted by MLeake
...A private seller, so far as I know, does not need to report the sale of personal property that is not used as part of a business. For the most part, I suspect private sellers often as not sell at a loss, in any case...
Selling at a loss is one thing. But it you sell something at a profit, that profit can still be taxable income.
It's probably true that casual sales of personal property at a profit don't get reported, and in general the amounts involved are probably trivial enough not to attract any attention.