Do not reply nor thank this "person" they never exist in the first place. You can insult it all you want, it will never reply.
How to tell if it's a porn bot?
1: Look at their avatar picture of a female posing sexually for the camera. Often times the picture is shared with the other bots.
2: Look at their DeviantID: If it says something along the lines of "dating" or "sexy" and what not.
3: Notice if their account is been recent, sometimes today, and sometimes a week ago.
4: They also made zero comments, because as said before, they never existed.
5: It's often a name of a person who never existed in the first place.
6: The bot will like your comment, regardless of the context of the comment itself. For example, you might make a comment that will make zero sense to the work itself (It could be a question or a single word) but the bot will like the comment anyway.
Instead: Block, ignore, and/or report.