Finding a place to stay in Spain during winter is really tricky: it's around 50-59°F during the day, but temperatures can drop to freezing at night (or even lower). There's no central heating, so everyone figures out their own solutions.

Some people install a boiler for their house, some rely on air conditioners with heating function, and others think that's good enough for tourists anyway (:

I once ended up in a place from that last category, and man, it was freezing. The owners just shrugged and said they couldn't help. Since I'd booked for almost a week, I had to do something about it. Escalating the issue on Booking surprisingly motivated the owners to buy a heater so we wouldn't suffer.

Most guests visit Spain during the warm season, which doesn't make it any easier to judge accommodations based on reviews.