Well, it could go eitherway. Somebody who gives a "My opinionz iz bettah then yourz" kind of vibe is a good example. Or somebody who somehow works for respectable publications but clearly doesn't know what he talks about. Your example is very good, so it's ok.
Now, the worst display of fanboyism you've ever seen is...
SUPERMAN 64!!!! I cannot stress how bad this freaking game is! I want to buy a copy of this game just to take a 12-gauge to it!! Between this and E.T. for the Atari 2600, there is not another video game this bad.
(I actually have a very good answer for this XD) The Friskies one. The song is just soooo bad. Oh, and when I went to watch Alice in Wonderland in 3D, I got to see that same awful commercial in 3 FREAKING D!! Well, it was pretty cool in 3D. But I still can't tell you the amount of times I've had "Friskieees! Feed the seensesss!" stuck in my FREAKING HEAD!! EDIT: I have a video to prove the awfulness.
Worst movie preview you've seen during a 3D movie.