Buying t-shirts(general sizing) online is fine for me.
But dresses...
I would prefer to try them on first before really making the deal.
Actually it depends which type of dress you're buying.
Formal dress I certainly wouldn't buy them through the net.
Cuz even wif all the info you still might find dat the dress isn't suitable due to cutting, material, color etc.
Also, what you see not necessarily will be what you get. ^^