Buying from Sample Sites

I can’t find this topic being discussed before so here it is.
I’ve been hooked to online sample sales like Gilt, ideeli, myhabit, rue lala. hautelook, etc for a month or so.
I’ve only been looking and reading up on the sites not actually buying anything yet.
Has anyone ordered from these sites? How would you review them? There are plenty of reviews on the net but I can’t seem to trust them as some of them seem to be heavily influenced or outright spam.
Anyone?