This: For very good reasons, most things we say explicitly carry a large boatload of implications, whether or not we actually mean them. This effect is exacerbated when people who say the same thing with the express purpose of conveying the implications - it becomes a widely-recognized signal.

It's still usually possible to approach the taboo in question, but it has to be done very, very, very carefully, like approaching a police officer who thinks you may be a violent criminal.