I hope you're not saying that you report losses on personal-use property. That might have to be done now, though, for people who choose eBay over yard sales. 

IRS will probably have a minimum for sending a CP-2000 on 1099-K transactions.  It will probably start out high -- maybe $20,000, so with income and SE tax, the assessment would exceed $5K and they could add 20% penalty.  The reason that $600 is the reporting minimum is that some people will get statements from multiple payers. Commissioner Werfel should be asked at confirmation hearings whether Schedule D will have a line for "amount of sales reported on Form 1099-K that were personal-use assets sold at a loss."  But he won't be.