Games on Steam Store then removed

Over the past year or two I've noticed there have been games I've seen or bought on Steam that have since been removed. Just kinda curious, what causes Valve to take down a game? Dispute with a developer?

Like I remember seeing the Decent ports on Steam but now they aren't. Also checked Clive Barker's Jericho, which I actually bought and is still in my library, but no store page and the last (well, only) News page being about a 50% off sale.

I believe a dispute with a developer or sometimes when enough bad press (being broken, etc) etc about a game being on steam will cause it to be removed, if only temporarily.