Quotation Marks for Emphasis?

It's really common to see quotation marks on words in advertisement to show emphasis. But what a lot of the advertisers don't know is the huge punctuation error they are making. The definition I recieved from dictionary.com says, "Either of a pair of punctuation marks used primarily to mark the beginning and end of a passage attributed to another and repeated word for word, but also to indicate meanings or glosses and to indicate the unusual or dubious status of a word." But that only confuses the brain. Things that commonly recieve quotations would include: a quote from another person, a conversation, and titles of either a book, movie, store, etc. Click here to see a site that gives good examples for this common puctuation error.