EDIT: FOR THE LOVE OF CHRIST AVOID MEGA SPOILERS PEOPLE. Just because YOU are recommending not to watch something does not necessarily mean it won't be watched, so please don't give away every detail of the ending in normal text. Please use light coloured text for spoilers.
Looking at all the Korean dramas there are, I realized that it would be very hard to watch ALL of them. Throw in all the Japanese, Chinese, British, etc etc shows I would like to watch as well, THERE'S NO TIME. So instead of adding to my huge list of dramas to watch, tell me some dramas I should SKIP and save my time on? Try not to spoil them, though.
My three skippable dramas, so far, are Secret Garden, Boys Over Flowers, and Playful Kiss. I actually enjoyed all 3, but looking back I didn't think they were worth all the time spent. Secret Garden is twenty episodes long, and while there were some moments where I laughed really hard or cried a lot, a lot of it was just watching the characters being silly. Boys Over Flowers is the longest I've watched and I remember very little of it.. so that should tell you something. I only remember that SPOILER: there were two beautiful, eligible boys going for the main character and she ended up with the worst option. Playful Kiss was cute and fun at first, but for the second half it becomes the typical back and forth non-drama. It was basically just the main character being vague about his feelings towards the girl and her moping the whole way through. And it was PAINFUL how SPOILER the cutest, most lovable character who was totally into her just got ignored.
EDIT
Just wanted to add my 2 cents on a couple of dramas I've seen mentioned in this thread!
Big - A lot of people are saying not to watch Big. I can see where they're coming from.. I wouldn't exactly recommend it, because SEMI SPOILER you wait so long for him to switch back, then the ending doesn't satisfy you at all!! My friend actually dropped it half way through. But I thought it was really cute and I enjoyed most of it, so if you're curious about it it might be worth watching.
Mary Stayed Out All Night - I thought this drama was pretty cute.. It wasn't my favorite and SEMI SPOILER it did leave a few things unresolved, like the gorgeous boy ending up with nothing! but I'd rate it a step above the pool of "I hate him!-why's he following me?-I kind of like him-why do I have to like him?-oh he hates me-maybe he likes me-not he hates me-" dramas.