Very curious to see what some people call a "guilty pleasure". I see a lot of people associating guilty pleasure with upbeat anime. But to be honest, I find that the upbeat anime are often way more sophisticated than the "oh no the world is ending!" blood splashed dark anime that's out there.
For instance, I'm currently re-watching Slayers with my girlfriend, and I can't believe how good it is! It's really well thought out, the characters are all very unique and original, and often surprise me. I'm also shocked at just how D&D it is, it has different names for spells, but that's about it. Not too far from Record of Lodos War. Lina is a very intricate character that defies a lot of tropes. How many red mage female characters do you know of in anime? Especially cutesy ones? Except for The Third, I can't think of any.
I also saw Lucky Star mentioned, which I also recently saw. I love "daily life" anime like that and Azumanga Daioh, which is one of my all-time favorite anime. Nothing guilty about that, Lucky Star is a great series. Another killer one in that category is Genshiken, an anime about anime (and hentai) geeks. I often feel that anime tries so hard to get away from daily life, that when a series does it, it's really refreshing.
I think of guilty pleasures as things that are ridiculously long and have mass popularity for mass consumption. They're not made to be very good, just keep people watching week after week, but also have some of their own charm: Inu Yasha, Dragon Ball Z, Naruto, some of the Gundams, I would usually say Bleach, but I actually thought the series was a good notch above everything else here.