They can tweak the subject to something not obviously spammy.

Obviousness in spam is a feature, they don't have to waste effort on people who know better.

This only applies to spam which requires significant follow-up effort from the spammer to respond to potential victims; effectively just 419 "advance-fee" fraud scams.

For spam which only does not require manual effort on the other side, there is no reason to filter out potential victims and all the more reason to make it look as legit as possible to maximize conversion rates.

	▲	takanot 5 hours ago \| parent [-]
		> For spam which only does not require manual effort on the other side, there is no reason to filter out potential victims and all the more reason to make it look as legit as possible to maximize conversion rates. Unless there's a trade-off. Saying "respond now or your account will be erased!" doesn't sound very legit. But the number of additional victims the phisher gets by doing probably outweighs the number of more sophisticated victims he loses.