There really isn't any blame to apportion anywhere but if it's insisted on then I'll place it firmly and squarely on the men involved.
We can think it gross but where and why are you apportioning blame to this woman? None of the men need to avail themselves of this service. Not a single one. What does that tell you?
Essentially, you're blaming her but have to pull back to blaming both the men and her in order to lash out at her (which is what all women seem to want to do).
This is a man problem. They want sex anywhere they can get it and that realisation is making women feel uncomfortable.