The reverse of not looking forward to something, then finding what you were dreading is not as bad as you thought, is when you really look forward to something and it isn't as good as you were anticipating. Like when you're a kid and you're hanging out for your birthday and then you get so over-hyped that you lose the plot, get told off and feel miserable!!
Not that there's any rule about any of this. Looking forward with anticipation to a big overseas trip (something I love to do), and I'm never disappointed. Sometimes I think that the reality can't match the hype, but it always does. I thought the Leaning Tower of Pisa would be over-familiar, and wouldn't have much impact on me. I was completely wrong - the lean on that tower was completely insane.