Scott Adams wrote recently about the increasingly poor online shopping experience. Every time you buy anything online you need to register, enter discount codes, work out shipping costs, struggle through endless attempts to sell you extra things you don't want...it's no longer possible to meaningfully comparison shop because every online retailer hides the final price in different ways, and it's already easier to just go to a damned shop.
My own frustration shoping online is with ad retargeting.
It comes back to the delusion of most website owners, that when people are online they are visiting your site. People are not visiting your site. They are on the web. If they don't buy the coat you're selling, it's not because they haven't been chased around the Guardian website by enough photos of the damned thing. It's because they bought another coat from someone else who was a click or two away. Just saying.
(Picture, let's face it, stolen from here)