This link is excellent. Thanks for finding it. 

Actually yeah, I think it's still possible out of band.

https://bitcoin.stackexchange.com/questions/10986/what-is-meant-by-bitcoin-dust/41082#41082

TonyGiorgio

I'm familiar with the mempool policy that won't relay a transaction that 

 dust transactions, but is it also the case that a block will be invalid if it includes a transaction that has a ~500 sat input?

bitcoin

There is no such thing as a dust UTXO

Scoresby

How so?

I'm familiar with the mempool policy that won't relay a transaction that *creates* dust transactions, but is it also the case that a block will be invalid if it includes a transaction that has a ~500 sat input?