You should do what you've been doing all along. Provide occasional reinforcement: post items urging people to look at the guidelines, urging people not to upvote naked snark, and perhaps urging them to downvote snark that seems to be catching on.

One or two comments to the effect of, "I agree with this, but the way it was phrased is toxic to the site, so I downvoted it" can't hurt either.

I don't think yours is a problem that requires a technical solution. You've already got a critical mass of people who give you extraordinary deference. Just use them to to fix it.