The brutality of the British (Black and Tans) is well documented and the ranks contained the dredges of humanity released from prisons etc, whether or not there were Scottish recruits among them is an irrelevance since they were wholly the scum of the earth.
Those who fell foul of their treatment in Ireland deserve much sympathy for their sufferings.
In Cyprus, the situation was somewhat different since the British were there much as they are to this day, those regiments which were staitioned here were posted for overseas duties, the persecution of the Cypriot population was seen as their 'Duty' and blind eyes were turned to any atrocities perpetrated by them.
As to the honesty of the Scots (in comparison to others) I cannot see any reason for there to be any significant difference other than, as individuals, the Scottish Regiments DO seem to carry a little more dignity with them than their English counterparts.
Or, could it be that bereft of pockets, the only way Scotsmen could conceal stolen goods was to 'Tuck 'em up your kilt Jock', a small handicap which acted as an assurance of honesty perhaps.