"Maybe that joke wouldn't be appropriate for your marriage"

It would probably be fine.

Of course, it's all a threshold game; if you're strong in other places you can get away with things that are technically a net negative, but you've got the buffer to deal with it. Every marriage if not every relationship does that since none are perfect.

But why blow the buffer on something so trivially stupid?

It also isn't really about "marriage strength", either, it's about basic human psychology. If you're talking about it, you're thinking about it. If you're thinking a little bit about it, your subconscious is chewing on it more than you realize. The most important message discipline is with your own subconscious. Don't feed it prompts you shouldn't. Even if you "get away with it", it's not free.