As I understand things, you don't get asked for your passport everywhere you go in Turkey for nothing - if you owe someone something (or have broken the law) the passport check at Dalaman is one of the places that could flag this up. Whether it would or not for SGK is debatable - their computer systems don't seem to be that reliable 
Yep, three or four years ago on around four or five occasions, every time we came on holiday scanning my husband's passport brought up a huge red warning on the security screen on arrival or departure in Dalaman. I know because the first time it happened I had already come through passport control into Turkey. They made him stand to one side and wouldn't let me back through so I stood behind the booth. His passport was whisked away and eventually men in suits came and let him through. We had the same experience when we left the country.
When we asked why a friendly little soul in a suit told us it was "because we can". It eventually transpired that his first name and surname corresponds with that of someone who they were looking for. Fortunately my husband has a middle name which the other person did not. Quite scary the first couple of times it happened and it became increasingly annoying thereafter. We met someone else in the same predicament one time - he had apparently been going through this for around six years and had contacted the British Consulate to try and get an explanation and the problem sorted.
There is a couple in Kaya who are leaving the country shortly and who have had an ongoing battle regarding SGK. They were told they could not cancel it and that it would remain "live" for the duration of their RP whether or not they were in Turkey. They have been trying to get their RPs cancelled and I think they were successful but there have been so many twists and turns that I wouldn't like to say the current situation or predict the final outcome.
