At one point or another, we've all gotten invitations in the mail for "free" weekend vacations or Disney tickets in exchange for listening to a short timeshare discussion. However as soon as you remain in the room, you quickly understand you're trapped with an extremely gifted sales representative. You understand how the pitch goes: Why pay to own a place you only go to as soon as a year? Why not share the expenditure with others and concur on a time of year for each of you to use…