Like many designers and developers these days, I set up a lot of blogs and web sites, often without enough time or budget to design a custom theme. Installing a free or cheap off-the-shelf theme is usually the best option.
And there are hundreds of beautiful themes available. Browsing Themeforest seems, at first, like an embarrassment of riches. But each time I mine the theme directories, flagging my favorites, I notice a problem: the details aren’t polished.
Out of every 10 themes with impressive and beautiful splash pages, it seems that 9 have fatal flaws which disqualify them from my search (often discovered only after purchasing and installing). Most are minor issues: a misaligned search box, a sidebar that deviates from the baseline grid, a lazily-chosen secondary typeface, unstyled page number indicators, and so on. But such minor issues often break the design’s gestalt, and prevent so many good themes from being truly excellent.
Of course, it’s likely that my graphic design background has hyper-sensitized me to some of these flaws, but design principles exist whether we consciously acknowledge them or not. A designer may recognize your theme’s awkward
h2 margins; a non-designer will simply move on to a theme that feels “right”.