For me, the last 4 "Coach" bags I have seen were fake. I guess it depends on your area of the country. I don't see too many brands besides Coach and Dooney in my area. It is pretty rare to see LV.
I guess,too, if it isn't a brand you know, you won't neccesarily know the bag is a fake. I saw a girl at Somerset mall in Troy,MI with a Chanel Cambon tote. I was thinking to myself, (I hope that is fake), because it was filthy. I can't tell you how irked I was by that.