This is an interesting topic and I don't quite know what I think of it.
If the government were to impose taxes aimed at curbing undesirable behaviors, we would probably want to limit it to those behaviors that are the primary factors in proven financial burdens on society. Which includes cigarettes and not porn, for example. The reality of it is though, that politicians and other influential types are so gifted in finessing bullshit for public consumption, that abuse and manipulation of the system would be inevitable.
Just as an aside, when I first glance at this thread title I thought it read: TEXAS to discourage certain behaviors. I have to admit I perked up at that.