I randomly browse all the time but have not really spent money that I shouldn't have. My browsing and purchases are different in that I browse all kinds of stuff but only purchase items that really appeal to me or my partner and even then I take forever to make my decision.
I definitely browse randomly... so far this has only led to one non-planned purchase, but I can see it being dangerous! I'm just glad that I have my wishlist as an outlet for the "ooh, I want that!" so that I don't wind up putting things in my cart.