I think quality slip on shoes such as tassel or penny loafers, in good repair and shine (tip of the hat to Mac and Jock) can look quite good with the kilt in semi dress situations and less formal wear but would probably not wear them with formal. I regularly wear slip on/clog type shoes from Merrel and Dansko on a daily basis when p@ntsed, but that is because of a specific foot spur problem I suffer from and the comfort they bring me instead of wearing closed heel shoes which aggravate the problem significantly. As such in casual situations I will wear the slip ons and not feel that they look bad.

I will not get into the fray about appropriate dress footwear as I only own a pair of ghillie brogues and wear them for dress occasions.