If you are buying for someone you do not know that well: pick a cartoonish title over an explicit one. Cute as F*ck and Adults Doing Adult Shit get laughs at a party. The porn editions are a different gift and they need a different relationship.
If it is going on a coffee table: check the cover, not just the inside. The cover is what everyone sees first, and these split hard. Some are discreet enough to leave out. Some are absolutely not.
If the person actually colors: buy for the paper, not the joke. Single-sided pages are the difference between a book someone finishes and one they abandon after two markers bleed through.
If you want them to learn something: the position and technique titles are the real ones. Kama Sutra Mini, Position of the Day Playbook and Bondage Basics come from actual publishers with actual authors, not the recycled clickbait that fills most sex-tips sites.
If you are building a bigger gift: a book is the cheapest thing that makes a box feel considered. It works for the partner who would never buy something like this for themselves but absolutely wants to read (or color) it. Pair it with something from Gifts for Her or Gifts for Him.