I diagree. You need question marks to keep a conversation going with a girl online.
True but, in my experience, you should also not ask boring questions just to keep a conversation going... leads nowhere real quick. Maybe that's what flint is getting at? If you just want to fuck, get to it sooner rather than later. If she's down, she's down. If not, there's really not much you can do.
In other words, if you can't think of anything to ask because the questions you WANT to ask would offend her... just ask them anyway. You might get more responses from a girl by playing it safe, but they're worthless, because the conversation will just fizzle out fast.