Yes, IF a guest should cancel due to reasons like i.e. conflicting events (i.e. new TV show/movie being shot and he/she is in there or in the case of Alice Cooper that he has a tour coming up for example), then you will be reimbursed for said photo shoot, the only time a ticket will not be reimbursed, is when you have bought a ticket for the comic con itself and the con goes on and you're unable to get there. It's usually only when the con cancels that they give two options - 1) tickets will be reimbursed back to your primary source of funding i.e. bank account or paypal and 2) the tickets will still be valid for the rescheduled comic con.