""
Quotation marks are not to be used to emphasize something. Because they don't do that. If a sign says "Saturday: 'HUGE SALE'" it makes me think, so what, it's not really a huge sale? Maybe it's not a sale at all? It's just a "sale"? Because quotation marks can indicate insincerity, as a stand in for the phrase so-called or something like that.
Also, you're not really supposed to use them to indicate scorn for words, e.g. Bush talked a bit about the "internets." Although, I do this all the time, and so does everyone else. I'm just sayin', my grammar book (Diana Hacker's A Writer's Reference, a pretty basic grammar and usage guide) says not to do it in writing, I guess you're supposed to use sic. instead. Feh.