a quick google shows that Mutton flaps are the belly cuts which are high in saturated fat
a brief read through the results suggests that they are cheap and nasty and are dumped on marketplaces such as Tonga, along with Turkey necks ex USA, as they can't be sold anywhere else. The WTO and WHO are trying to curtail this practice owing to the increased obesity in these countries since the practice of food dumping has taken off.
Mutton flaps are indeed the belly cuts from sheep or lamb and yes they are high in saturated fat. They are realistically like any other meat, if you are educated on how to cook it right and minimise the fat that you intake after the cooking process they are delicious. Slow cooking is the best way to cook them, I trim the meat away from the exposed fat and then re-wrap the meat in the skin that is remaining from the outside and slow cook it in an oven tray over a rack. It's really like any meat the meal is in the preparation if you are not told how to prepare it properly and/or where to take the best cut from the base product after cooking you will end up with an unhealthy meal. My personal philosophy is don't be rediculous about cutting out some of the best tasting meat cuts and foods in the world because of the hype around saturated fats, match your meal with a double helping of vegetables and look after your body with regular exercise and you can enjoy some of the things that other people will never know the tast of, KMH I agree with you that food dumping is an awfull practise in countries such as tonga and samoa I have seen this first hand, but it is like anything in this world without education too much of it will kill you in the long run. P.S. I am talking from a perspective from someone who has his own home killed organic meat and I love BRO TOWN....