Actually, I can easily imagine that many claims with no truth at all. This could be a bunch of women who wanted fame, never made it in Hollywood, but met Cosby, and it's not hard to imagine one woman making it up out of spite, desperation, or a desire to be noticed. Once the first one tells an invented story, it's easy to imagine the rest joining in to be noticed. [I'm not saying that's what happened. It's just as easy to imagine a powerful entertainer feeling above the law and preferring drugs/force to simple seduction of willing groupies.]
One woman filed a police report in 2000, and one in 2005.
In 2005 he was accused of drugging and raping a woman in 2004, and settled with her in 2006, after 13 more women surfaced who would testify to his rape methods.