"Youd be surprised at how much incorrect info you can give on some sites even when making online purchases and still get the purchase through ok. "
Of course you can. That isn't the point. If you are on a social networking site such as Facebook, and your name is Basil Willrun, you call yourself Norman Bloggs if you like but I'd question why you'd want to do that.
All my facebook friends, and everyone else I know who uses it, use their real names.
If, on the other hand, you don't need to give your address or any other personal details then it surely makes sense to leave them blank.
If you're buying something from a mail order company online you will generally want to give them your address if you're expecting a delivery from them. If there's information they don't need but you are obliged to give then by all means put in any old rubbish.