One of my favorite types of inappropriate quotation marks usage is the application of didn't-get-the-joke? quotation marks. Here's a demonstration from the La-Z-Boy Web site:

"Never content to 'rest on our laurels,' La-Z-Boy has maintained a commitment to quality and craftsmanship for over 70 years."

Apparently, the writer of this passage has little faith in the intelligence of his/her audience to be able to pick up on the pun on their own.

Oh, and in case I've misjudged my audience's intelligence (and I don't think I have), I'm using the word "favorite" in the first paragraph in a sarcastic manner....didn't-get-the-joke? quotation marks are actually not one of my favorites.