Using Autotune on Mixpad Multitrack

Auto-Tune is getting way too popular these days, as you can read in this part of Wikipedia:

In 2009, Time Magazine quoted an unnamed Grammy-winning engineer as saying, "Let's just say I had auto-tune save vocals for everything from Britney Spears to Bollywood cast albums. And every singer goes now assume you're just letting his voice roll through the box. "

American television series Glee is known for the regular use of the system in their songs. E! Online's Joal Ryan criticized the show for its "over-produced soundtrack," and complained that many of the songs were overly software-dependent.

Controversy arose in 2010 when UK reality television show The X Factor was accused of using auto-tune to improve the voices of attendees, particularly Gamu Nhengu. Simon Cowell ordered a ban on auto-tune for future episodes.

- Wikipedia - Auto-Tune - review

Having grown up with auto-tuned pop songs, I find it difficult to tell if auto-tune was used on a recording. I can clearly hear glitches on some tracks on Glee due to overuse of the Auto-Tune effect. But if it's not used that much I have no idea how to find out if it's been used or not.

From an audio production perspective, it would be nice to know the difference between a normal recording and how can I tell this difference instead of being fooled?

If this effect is needed to compete with the current top songs,
or are there songs that are not used auto-tuning in the diagrams?