That’s an interesting question. At the conference I just went to, there was a lot of talk about if being a skeptic automatically means you should be an atheist. The general consensus was that an atheist is someone who is skeptical of one thing; the existence of god.
So, my answer is that my being an atheist has no bearing on if I believe in ghosts or not because being an atheist is about non-belief in god(s). As a skeptic, on the other hand, I seriously doubt the existence of ghosts because everything I’ve seen tells me that there are far more plausible explanations for what people would call ghosts than disembodies spirits.