A great spot is Granville Road in Kowloon. It has a number of shops where the factories producing big brand goods send there sample stock and run offs. Possible to get some genuine big label branded items for a fraction of normal price. I bought some Nautica clothes a couple of years ago and they are still going strong now.
There is a lot of junk at the night markets on main stalls but the shops behind the stalls have some good finds for things like jeans. about 6 years ago