[Henk0]

My guess as to why swearing in particular is easier would be that it’s mainly due to classic conditioning. When you’re a kid, you tend to learn through punishment (e.g parent telling you off) which words are not acceptable before you really understand what the words mean. Being told off is an aversive stimulus and you form an emotional association to the sound of the word. Later you might learn that these words can be wielded to excite others too, either to make them upset or to just to increase the emotional impact of something you say. In a second language, you’re less likely to have been conditioned that way, or at least as strongly. Regardless, I’ve definitely noticed the effect myself with English being my second language, even though I do swear a fair amount in my native Swedish too.