1. I hear "nobody understands the Coase theorem" way more often than I hear that a Coasean world is one with zero transaction costs (in fact I can't remember when I've heard that one, although I'm sure I have somewhere along the line). That has to say something for the validity of the first statement.
2. The naïve Coase theorem and the actual Coase theorem seem like corollaries to me. So all you're really saying is that Coase thought the latter was more interesting. That seems to deflate the meme considerably.
3. I only ever seem to hear the meme from people who like to expound upon misunderstood traditions in economics. That also seems like it says something about the validity of the meme.