You should make it clear on your profile page and let your potential clients know upfront what you are willing to do and what you will not be doing under any circumstances to avoid any possible misunderstandings. The case is that when you sign up for a live sex chat website, posing nude is considered to be part of the job. And even if you do not feel like doing it, which is completely fine and to be respected, understand that you sabotage yourself in a way by letting everyone know that there will be no nudity involved, which may send the viewers in search of other camgirls and spend their money elsewhere.