The best thing to do with pure spam questions ('CHEAP NIKES' etc) it to get rid of them as fast as possible.
This can be done by the community casting 6 spam flags against the post. However, each spam flag also casts a downvote against it. People can also downvote posts they have flagged, or just downvote the spam post without flagging it as spam. After 4 downvotes the question will disappear off the frontpage but still remain open / undeleted. This means a spam post can theoretically accrue more downvotes than spam flags, and thus disappear off the front page of the site they're posted to.
This is bad.
We need spam to be removed altogether, not just hidden from the frontpage. If a post is hidden then it's less likely to acquire spam flags and will theoretically stick around longer than it should to.
I see no overall benefit to the site for spam posts to accrue downvotes. It's a hindrance more than a help really. People are free to downvote what they want, so we can't stop people downvoting spam. But we can stop spam flags from auto-downvoting.
So that's my suggestion. Remove the auto-downvote feature from spam flags. Unless someone can give me a good reason as to why downvoted spam is better than deleted spam.