As the owner of a small B&B can I beg people to book direct with their accommodation!
The big OTAs like booking . com, expedia, tripadvisor et al charge huge amounts of commission - 15% is standard, but this can go up to 35% during periods of high demand, i.e. Hogmanay in Edinburgh or London when the marathon is on. This means we have to increase our room rates to cover the commissions (10% commission across the travel industry was standard for years - when you had actual people doing the work of finding your accommodation/flights etc, why there is a need to up the commission so much when it's mostly algorithms doing the work is beyond me).
Also, a friend who runs a guest house in a very popular tourist area is pulling her hair out because people are booking 2-3 different places with the OTA's for the same night, turning up in the city, seeing which accommodation meets their needs (is more central/close to restaurants etc) then cancelling all but one of them at the last minute leaving her with empty rooms.
When you book through an OTA, we don't get paid by them until 2 weeks after the end of the month in which you stayed - so if your booking is for 2nd July, we get paid mid August.
We've also had a spate of chancers booking through OTA's claiming the booking is for 1 person then 2 people turn up. It's difficult to resolve/get the extra money via the booking company.
So please, if you can, book direct with the accommodation - you'll probably get a cheaper rate, and you have more comeback if it's the accommodation who's buggered up your booking.