There's only one way to deal with spam. Ignore it.
Perhaps you have something more interesting to do with your time.
I don't think it's a good idea just to ignore it. this spam may cause some problem to people that is not aware of it.
Correct, this is spam, and how do we deal with email spam? With filters in order to reduce the noise, spam filters have become so effective that only one out of 1000 reaches its destination. So there could be a way to implement something similar in the Bitcoin Core?
But sometimes legit emails are marked as spam (once a professor received one of my emails in the spam folder, I do not know who the hell reported me as a spammer since I never forward stupid mail chains nor spread propaganda, etc.), I mean, how would you distinguish between real (dusty) transactions and spam? If bitcoin is going to be only for big transactions, a lot of people (like me) will forget anything about it.
Well, my comment was just an analogy; Im not such an expert in bitcoin to try to recommend any kind of solutions. But I still think its a good analogy.