My favourite is to sound interested, go through all the details, even give them false details and then finally at the very end admit to the false details and just say "Well as you've wasted my time I thought I'd waste yours"
Remember they're on commision, they try to withold thier details purely due to the fact that they know they're doing something wrong.. So string them along, waste thier time and reduce thier sales and calls for the day
