From my experience many of the owners are involved in referral pools with other owners and will forward your request to other owners in their group(s) if they don't have availability or meet other criteria. In return they receive referrals from the others in their group. It has plusses and minuses. For the owners they benefit by getting referrals from other advertisers/owners, but may lose out due to people seeing empty calendars and being suspect. For renters, you may find the property you inquire about is booked but receive e-mail from other properties that do have availability and meet your criteria. The downside is that you get a lot of e-mails often without references to vrbo or other property #'s etc, wonder where they came from, and sometimes receive more e-mails than you might wish for. One such inquiry netted me some 30 e-mails one day. Personally I like seeing the availability right out front and would prefer an "opt-in" link to the owners group referral as an option. Something like a link with "If we don't have availability on your dates, click here to receive info on other properties that may meet your requirements."