Probably a waste of time. When some one twigs what is going on they will use "T H A N K S"
I'm not trying to catch out people who are trying to catch me out. I just want to catch people who are in auto-pilot mode. As soon as a member starts doing what you're talking about, he'll get one last laugh, and then the boot.
I don't fool myself into thinking that such a filter will catch all instances of flagged terms, but it may catch enough of them to make it worth while.