one of the main things we consider when using VRBO/AirBnB, etc. is the cancelation policy, which varies by unit/owner...some are pretty strict, only allowing cancelation during first 48 after booking, and others offering a longer period for cancelation....some give 100% refund, some will withhold service fees...you really have to read and understand the policies of the particular unit you're considering

in several cases, after renting through VRBO the first time, and getting to know the owners, we've consequently rented directly from the owner for future trips, usually getting a better than published rate, as well as avoiding service fees...saves money, but there is some risk as you then don't have the "support" of VRBO if things go wrong and/or you need a refund