One of my peeves in marketplace is the inability to narrow my search by using Boolean operatives in the search window. Just being able to add something such as -demo would save a lot of time and bother.
Another is this recent thing of using a picture that shows someone's entire product line with the particular item highlighted (or not), usually coupled with the word "rare" in the description and a jacked-up price. First of all, it's only rare because the builder decided to make it so. And if it is, indeed, rare and valuable, shouldn't it get its own photo that shows it in detail?