maan Pokemanz don't even count as a guilty pleasure except in the most stifling of social circles. In high school they may be a little bit taboo but typically after high school is over it's all "YEAH POKEMANZ RULE" again, even if it's just for the nostalgia purposes.
One of my guilty pleasures is studying martial arts, but only because I'm at a very low rank. I definitely keep my practicing private/semi-private so no one makes fun of my utter lack of skill.
Runescape, kind of. I used to be hopelessly addicted, about 8 years ago. My character's still there, I know the password, and sometimes, when I am weak and susceptible, the siren song of absolute mindless repetitive skill grinding calls out to me. I'd log on, do something repetitive for about an hour to get my fix, then log off and pretend it never happened.
I don't play any MMORPGs of a higher quality than that because I am fully aware that something like WoW could consume and ruin my life if I tried it. Although I did have a Silkroad Online stint for a while.
Fantasy is kind of a guilty pleasure, but it's less about the genre in general and more about particular works. For instance, I really enjoy The Wheel of Time by Robert Jordan, but I realize in some circles I should keep that information tightly concealed.
And finally, DF is a guilty pleasure, but only because my RL friends are sick and tired of me talking about it. Haha.