My mom bought the Dino Horde games on Steam for my family for like, $40-60, and the very next day it went down to 99 cents. I wasn't going to tell her because I knew she would feel really bad about it, because I've done that so many times. But my sister went ahead and told her like, IMMEDIATELY after. I was like, why the heck would you say that! Sometimes it's better to let them be ignorant about things.
Also, hmm. Yeah, I'm sure there's quite a few. The only games I bought recently-ish that I disliked were in Humble Bundles, so it's not like I paid much/intentionally for them.