I’d always thought that “dusting” was an urban legend, except that so many smart people report receiving these mysterious transactions.  It would be an awfully expensive way to do blockchain analysis; and dusting an address that already contains coins makes no sense.  The coin you already have can be tracked:  Where it moves to, what change it gives, what other coins it may merge with, etc.  How does merging another UTXO add any information helpful to the spies?  What am I missing here?  (The biggest privacy killer is, IMO, coin merge from one’s own change.)

Dusting an unused address that is advertised somewhere seems more useful, albeit expensive.  Then, the coin can be watched for what it merges with.  (Donation addresses, forum signature tip addresses, etc.)  Dusting an address that previously had coins seems it would be very helpful to the spies, for the same general reasons why address reuse is a bad idea.

Anyway, if you really don’t want that mysterious dust, then please consider disposing of it by burning it in an OP_RETURN, and/or donating it to miners as fees.  This helps Bitcoin by removing those outputs from the UTXO set.

I recently went on an extended rampage in Development & Technology about how OP_RETURN is the one and only right way to burn bitcoins.  (In that context, explaining why so-called “burner addresses” are harmful.  Interrupted by losing my BTC.)  Some of what I said there is relevant here.  Starts here; thread is a kind of a dumpster fire, by dev forum standards.  I need to get back to that.

(OTOH, not many people would do that; the anonymity set of people who burn dust in OP_RETURN is probably small; the anonymity set of people who donate it to miners as extra fees is probably larger... hmmm, so many privacy problems.  It is why I want strong privacy built-in on L1 in Bitcoin.)