I've lived in Scotland for almost 6 years. I've lived in 3 cities. When we were looking for an apartment just before Sebastian was born we looked in about a dozen different areas surrounding Glasgow/Paisley/Greenock. We never once found a furnished apartment. There isn't a market for it.
Aberdeen is a whole different ball game. We couldn't find anything NOT furnished. I asked our estate agent why this was and she said that it all has to do with the oil and gas industry and Aberdeen University. Aberdeen is a very transient city. People move in for just a couple of years and then they move back out. Their job is done. Not to mention how expensive it is to live here! There is a huge market for serviced and furnished apartments. People are paying big money to have everything taken care of for them.
We live in the city centre so that is more of the reason why we found a furnished flat. It makes sense that people want to be close to their places of work/study and that they would be the ones to need such places. To find unfurnished places you'd need to go out of town. Even then the ratio is 5 furnished to 1 unfurnished. It is what it is.