Re: Mars Bar
There are chip shops in touristy areas that will sell them to anyone daft enough to want one (I think there is at least one of the chip shops on Edinburgh's Royal Mile that does), but, yes, I'm pretty sure that hardly anyone eats them normally.
Deep fried Mars bars were invented in a chip shop in Scotland, the story got picked up by the media, and so there was a brief fad of some people being curious to try them. Sadly, the "legend" still lives on, as these things tend to do.
There is at least some truth that chip shops (possibly not just Scottish ones) will dip all sorts of things in batter and fry them (hence the horrible deep-fried pizzas, which really ought to make any self-respecting Italian-Scot chip shop owner feel the shame of many generations of their ancestors upon them). On the other hand: pakora! Unfortunately, the fact that "munchie boxes" (look them up) are quite popular items in some chip shops sadly speaks for itself!
Biting the hand that feeds IT
