Not convinced this isn't falling into Complaining About Shows You Dont Like — we don't have the general agreement of that special horribleness required.
the High School Musical trilogy. This troper took it seriously and loved it when it first came out. (Keep in mind I was 12 at the time) Watching it 5 years later, it's hilarious. Especially the third one. Over-the-top musical numbers? Check. Cheesy plot? Check. Less than stellar acting? Triple check.