Typical Sun attempt at rhyming headlines!
I think they have taken the word "grotty" meaning "dirty, poor condition" and rhymed it with "Scots."
They might equally have used "Grotty Scottie" for example.
It would still be a perjorative twisting of the story especially as there are cities in Wales and England in the list.
No indication of the size of the survey nor how it relates to the population of the individual cities.
What's grotty is their headline! 
[B][COLOR="Red"][SIZE="1"]Reverend Earl Trefor the Sublunary of Kesslington under Ox, Venerable Lord Trefor the Unhyphenated of Much Bottom, Sir Trefor the Corpulent of Leighton in the Bucket, Viscount Mcclef the Portable of Kirkby Overblow.
Cymru, Yr Alban, Iwerddon, Cernyw, Ynys Manau a Lydaw am byth! Yng Nghiltiau Ynghyd!
(Wales, Scotland, Ireland, Cornwall, Isle of Man and Brittany forever - united in the Kilts!)[/SIZE][/COLOR][/B]
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