We have a vacation rental located on the Big Island of Hawaii thus I am a property owner and also a traveler.
Most listing site charge travelers a booking fee to book from their site ranging from 5-15% over and above the total of the rental price of the rental. Sometimes it hard for travelers to see this fee is getting charged to them but it is there.
AirBnB, Tripadvisor, HomeAway and VRBO are a few of the larger ones that I know all charge travelers a fee to book.
As a vacation rental owner the fee's for owners to list on the sites are as follows:
AirBnb they charge owners 5% of the rental amount
Tripadvisor = 3%
HomeAway and VRBO (owned by same company which is now Expedia and they were just bought by them for 3.9 billion) charges property owners either a yearly subscription ($399 annually) or owners can choose a pay per booking which is 8%.
I do get bookings from all of the above but I prefer when guests find our rental on one of the sites I listed below. If guests do want to book from one of the paid sites. I do request that they tell me a little bit about themselves and their travel plans before I accept their reservation request. Otherwise no way to know if your renting to a bunch of young adults wanting to hold a stag party or something in your home.
Being a vacation rental Homeowner and also a traveler. I prefer to receive bookings from guests and book my lodging from "non fee" sites. Me as a homeowner and many of us homeowners feel the same way is we want to have control over our property and who stays in our home. So preferably we like to receive bookings from some of the sites below that do not charge the traveler a fee and are all free to the traveler. Some of the sites below property owners are charged an annual fee to list. I myself when booking property I do want the ability to speak with the owner direct prior to booking so I can see if the property is a good fit for my vacation.
There are more fraud properties listed on the paying sites then the free sites.
Free listings sites are popping up all over due to the buy out of HomeAway and VRBO to Expedia.
Here are some free listing site to which you can still book direct from the owner and contact them etc prior to booking.
www.homeescape.com
www.VacationHomeRentals.com (Part of Tripadvisor but do not charge travelers a fee)
www.unitedvacation.rentals
Vacationstayz - Find a vacation rental with no service fees
And if your a member of facebook I suggest to join this public it is for both vacation rental owners to list their properties and travelers looking to rent can search the properties along with submitting a "rental request"
https://www.facebook.com/VacationRentalsfromOwners/
Hope this information helps.