Something you know that is bad for you, but you do it anyway…
Me = junk food
I really like to make out with my ex-wife. We’re on good terms, just can’t cohabitate.
If she’s not around I’m always up for a 12 pack of beer, a few plates of nachos & any Lord Of The Rings movie.
TiVo.
I don’t have guilty pleasures. It’s because I have no shame, really.
Driving my car… like it’s stolen. 
3 egg omlettes with bacon, onions, home fries, toasted garlic bagel and strawberry jam. And a Dr. Pepper.
Really well tailored suits and great shoes.
Downloading MP3 music for pennies a song.
Posting on the SDMB while at work. :eek:
I’m with Silver Fire. No shame at all. 
My occasional trips to Reno. I feel like I should be taking the kids with me, but it’s not a kid place. And I am not doing family stuff while there. But still…
Eating WAY to much candy
Well porn obviously.
Being by myself.
There’s friends that are constantly wanting to catch up; I have a great housemate who I get on really well with; there’s the dog to be walked; there’s people from work who want to meet up, too.
But sometimes I just take off into town, or go for a walk by myself, or even go and see a play by myself.
And I feel guilty because I think this would be a good opportunity to fulfil those social obligations I never asked for, or to feel like a better pet owner in the dog’s case.
But I just love being by myself for a few hours, because I’m never alone unless I’m driving in my car.
Sleeping late.
Everytime I do it I kick myself for the next two days while my sleep schedule is messed up.
Ohhhh, but it feels sooooo gooooood to laze around in bed while the sunshine beams in through the window. Ahhhhhh.
Grossly overpriced cosmetics, Robert Mitchum movies, rum blender drinks, exploitative porn.
Candy. Toffee almonds, Jelly Bellies, Swedish fish…I can’t seem to stop myself.
Zelda on super nintendo.
Toasted sandwiches made from english muffin, marmite, summersausage, 4 year old cheddar, a poached egg, chipotle hot sauce, butter, salt, pepper, and onion powder.
Talking to pretty girls.
Well, I really can’t tell you here, now can I???
But to respond to the OP, buying plants and supporting my zeal for unusual botanica would be the guilty pleasure that I can admit to publically.
I’m a big fan of the Trailer Park Boys.
Listening to Jeff Buckley.
Making politically incorrect jokes with my friends.
Air America Radio.
Femdom porn, gangsta rap, ramen noodles, potato chips, cheesecake.