At present, it takes three spam flags to get a question suppressed from the front page. On smaller sites getting this many may take a while, especially during the 4-12 UTC period of high spam / low activity. Recalling that Tim Post wrote
Once it's been identified as spam, we want it off the front page.
I suggest the following: if a question is posted by a new user (defined as reputation = 1, or in any other convenient way), it should be hidden from the front page when it has even 1 active spam (or rude/abusive) flag.
Benefit: cleaner front page even during spam peak.
Potential objection 1: not as many users will see spam posts to flag them. But hiding them is the top priority, since eventual deletion is assured even after one flag (as a result of mod review, if nothing else). For those looking for spam, the /questions page is already preferable to the front page.
Potential objection 2: a hypothetical rage-flagging user may temporarily hide some posts. But rep=1 requirement would mitigate the damage, and such a user would quickly lose the flagging privilege.