They need to be fitted and paired correctly with a shirt and tie, or just a shirt. V-necks or button ups. Now I'm talking about dressy vests not sweater vests. You can choose to keep it buttoned up or open. Unbutton the first few top buttons on the button up shirt or if you have a V-neck then it is done for you already, but you want a coordinated dip with the vest and the shirt having the shirt a bit longer than the vest and peaking out. There are vests that are a cross between a sweater vest and a button up one where it has a long dip at the neck. And don't forget to wear a short sleeve shirt or a 3/4 sleeve shirt!