I think if they are playing a role it's fine. If I was an actress I personally wouldn't like playing roles with a lot of cussing or other non-biblical activities.
Lying really is about the act of deceiving and not about speaking non-truths. A person can tell a non-truth, but if they thought it was true, they weren't lying. When acting, you are playing the role of a character and the audience understands this. Conversely, a person can tell the truth, but shape it in a way to deceive. Even though the said everything right, they manufactured deception and were lying.
I don't think so, but I do think that an actor should be careful when in roles like that, since what they believe could be corrupted.
One thing that I've been doing recently is, before playing a game or watching a movie that has really bad parts in it, thinking "Does this honor Christ, or does it have bad elements that affect the whole thing?" If it doesn't honor God, then I ask myself, "Do I treasure this thing more than I do Jesus?" That's the question that decides it for me. I know that almost everything is going to have some elements in it that we disagree with, but if there are so many or they're so bad that it pervades the whole thing, I think it should be avoided. After all, is it worth it?
Now, I've been kind of going off on a tangent here, but in final response to the question, no, I don't think that playing a character that doesn't necessarily represent you is lying. After all, I played a foolish jester once and... well, I'll leave that to my friends to decide.
"There is therefore now no condemnation against those who are in Christ Jesus. For the law of the Spirit of life has set us free in Christ Jesus from the law of sin and death."
--Romans 8:1
Prudence must be key here. What is the intention of saying something true about the character but not about the actor?
I can understand, for example, why it would be harmful to say off-stage in public that you are promiscuous (as your character) when in real life you are chaste. Why would someone say such a thing when he is not required to perform? Does he wish to become more promiscuous? Does he wish to garner false and unnecessary attention?
These might be things which make such a falsehood wrong. But I can't imagine there's a general rule on such a thing.
I feel this passage from the Catholic Catechism illustrates my point succinctly:
The gravity of a lie is measured against the nature of the truth it deforms, the circumstances, the intentions of the one who lies, and the harm suffered by its victims. (#2484)