I am wanting to buy my first pair of Coach sunglasses. Specifically the Sofia ones. I currently own just 3 Gucci sunnies and they are all I know concerning sunglasses! How well do they hold up? Another pair at the boutique had like one of the legs swinging really loosely like it wasn't tight at all. I'm afraid of the quality... I was just really put off by that one pair where the leg was swinging madly all loosened. Any problems with the sunnies by Coach? Thanks so much.