Booking.com and Hotels.com and other travel sites have delightfully bad algorithms. I am currently getting spammed by these sites because I recently used them (or have done so in the past).
The only information they have about me is places I've travelled via bookings through their sites, so they just keep recommending me deals to the same places.
The funniest was when I got a recommendation for a hotel within an hour of checking out of that same hotel.