Meaning of 脏话 in 这里能说脏话吗
From my point of view, 「这里能说脏话吗」may have several different meanings in different contexts.

Ask other people whether he can swear in the chatroom.
In this case, the person asking the question wants to talk rudely in the chatroom.
It serves as a rhetorical question.
This person may have seen some people talk rudely in the chatroom. So he said this to remind other people that it is not allowed to speak rudely in this chartroom.
「我能说脏话吗」&quot;Can I speak X?&quot;
This is most commonly seen online. It's widely used that in fact this phrase has become an online idiom among Chinese people.
It origins from a passer-by when asked by a journalist of his opinion about increasing gasoline price:
「我能说脏话吗？不能？那就没有可说的。」 &quot;Can I speak X? No? Then there's nothing to say..&quot;
Now Chinese people use this phrase to express dissatisfaction about something especially when under some kind of censorship.