For shows, rarely—I usually just go by what I've heard people say about them, then I look at summaries/content warnings to see if it's something I might be interested in. I look at gaming reviews more often before getting games, but generally just from a few specific bloggers whose tastes generally align pretty well with my own, and then decide from there. Sometimes I adore games that only have lukewarm/mixed reviews, so I don't base my decision around reviews entirely.
I also look at product/seller reviews often before buying something online. I want to make sure I'm buying from someone who seems trustworthy, and if I can't physically examine an item myself, then I definitely want to hear from people who have. It can still be a little hit or miss, but I'm usually pretty happy with my online shopping experiences so it's not a step I'll skip out on.