I have a family with more than a few tax people and have talked to them about this.
The 1099-K is an info document. The IRS gets a copy so it should be accounted for. All monies reported on a 1099-K isn't income. Sometimes it is, or isn't, or just a portion of it is. It's the responsibility of the tax payer to make that determination and report it properly.
They told me that for a nonbusiness, selling personal items, the money reported on a 1099-K of this nature does not represent income and there are two choices:
1) don't report it on your tax return as it's not really income, if you're sure it's really not,
2) report it as two miscellaneous line items, one showing the income amount and a second as a negative, or loss, to show net zero income. They also pointed out that any actual loss from selling an item for less than you purchased it for in this case cannot be claimed as a loss that reduces your liability. This type of income can or cannot add to that liability only.
In either case, they suggested I should keep documentation sufficient to prove that the reported amounts are not income, that is, were sold it a loss, in case the IRS demands proof later on.
They believe that the purpose of this is to increase compliance but that people will find a way around it or that thethe mass liability has been grossly miscalculated by the government. This will cause them to "overcorrect" or step up compliance efforts as the expected increase in tax revenue is not experienced. This may include audits or further rule and policy changes.
It's really PayPal policy that seems to exempt F&F transactions. The IRS and the 1099-K doesn't care. It reports all transactions above the threshold and the taxpayer accounts for it appropriately. With a quick change in policy, PayPal could report all positive transactions on a 1099-K and let the taxpayer claim and properly characterize the income as required. That would mean F&F would suddenly be reported and you'd likely be wise to go with option 2) above.
PayPal doesn't care one way or another. It's a bit of code in a computerized system and the fact is, these rule changes might scare some people into opening business accounts or getting people to use F&F and G&S properly. This makes PayPal more money.
Just wait until your bank accounts are similarly monitored and that will catch Zelle, cash transactions, money orders, etc.
Anyway, my discussions with my family don't have me feeling very good about things. Part of me wants to just do it and be done with it. I could have sold three of my watches a few times over if I'd use PayPal. But the other part of me says I'd be the one they'd catch and give a hard time.
All I can say is be careful and be prepared. Protect yourself.