It's not very clear when you use what I call the 'smirk' emoticon, as it can get mistaken for someone who wants to adopt a superior position.
Many people would react the same way to that post of yours, especially when it alludes to delicate subjects such as porn.
Maybe people should make it more clear when they are apparently attempting a harmless joke.
That particular emoticon is called a wink, as opposed to 'big grin', and 'smile', or even a bracket saying (joking), which would all make it clearer.
Wink implies that the subject of the 'joke' has in fact done something wrong or inappropriate, and that you are letting them know as such, but playing at keeping it a secret.