I don’t know if anyone ever tried giving a sermon on the verse. The Bible I have says:
Do not give what is holy to dogs or toss your pearls before swine. They will tramble them under foot, at best and perhaps even tear you to shreds.
Because Christ often spoke in parables, he would convey a different meaning from how he was expressing something. And swinish can mean ‘gross and brutal’ He may have meant;
Don’t try give what is holy and valuable to ones’ that will try to destroy it and maybe you, because they will try to destroy it just because what you have is holy and valuable.
I know you brought up the verse because of what Blueocean said, referring to the way some people react, maybe they are just jealous because they lack a stong faith.:)
Anyway, that’s my thoughts on the verse.