Getting UX right is much like picking up girls (and I was never good at it; the picking up, I mean): charm is important, but it has to be backed up by right thinking.
I experienced the same when browsing iStockPhoto for an illustration. I searched for “startup” and my eye was caught by this:
Nice, but how do I purchase it? There is a big, shiny “Buy 1 credit” button, but I’m not sure what a credit is and why it is $12. But more importantly, I’m irritated by the thoughtlessly placed plus sign. Here it is again:
What is it supposed to do, I wonder. Is it an enlarge action? Add to cart? Something else?
What’s most irritating is that if you hover on it, it says “Add to lightbox”. Now, lightbox is a fairly sophisticated term, used exclusively by web designers and front-end developers. But even if you know that a lightbox is a translucent box for displaying images and videos interactively, you wonder what’s the use here. Will adding to the lightbox enlarge it? If not, what will? And if you click on the plus button, it asks you to log in / register!
I don’t understand what was wrong with labeling this button with the actual action it performs. If I was the designer, I’d just add a soothing, “Add to cart”, or “Enlarge photo” right below the button. I don’t think it would kill the look, but it would greatly simplify matters for the user.