There is little disagreement that wearing a tie without a jacket of some kind looks bad. This is true whether or not the shirt has French cuffs. The more usual question about French cuffs has to do with wearing them with a jacket, but without a tie. I personally think that they look pretty awful without a buttoned-up shirt and tie. One then might ask whether one has to be wearing a suit--as opposed to sports jacket and trousers--to warrant French cuffs. On this you'll get differences of opinion. For me, as long as I'm wearing a jacket (suit jacket or sports jacket) and tie, I like French cuffs. With sports jackets I usually wear silk knots in the French cuffs, whereas with suits, I wear metal cufflinks. For most dress occasions now, I wear French-cuff shirts, as I prefer them to button-cuff shirts.